Jeremy Corbyn was never expected to be the leader of the UK Labour Party, until he was. He was never expected to last in the role, until he did. He was never expected to seriously challenge Theresa May and the Conservative Party in the 2017 election, until he did.

And he is never expected to be prime minister of the United Kingdom.

Corbyn is a left-wing member of Parliament who calls himself a socialist; who’s had decades in politics to accumulate a lengthy record; who’s been haunted by charges of anti-Semitism in his party; who was called everything from a “big girl’s blouse” to “Joseph Stalin” by his main political rival just this year; who’s been noncommittal about Brexit; and who’s currently the most unpopular opposition leader since people have been tracking these things.

So he’s not someone who could ever really be prime minister, right?

And yet maybe, it could still happen.

The United Kingdom is holding general elections on December 12, in what Corbyn himself has called a “once-in-a generation” vote. Corbyn will lead the Labour Party against Boris Johnson, the current prime minister and head of the Conservative Party.

The political stalemate over Brexit — the UK’s divorce from the European Union — finally forced lawmakers to agree to elections in October. Prime Minister Boris Johnson wanted a vote. He lost his party’s majority in September, which derailed his plan to get Brexit done by October 31 and meant he’d likely continue to struggle to pass his Brexit deal in Parliament, let alone any other legislation.

Labour lawmakers supported an election somewhat reluctantly. Corbyn is a huge reason why.

The opposition leader is stunningly unpopular. Corbyn’s approval rating hovers in the 20 percent range. That’s remarkable, especially because Johnson himself is a pretty polarizing figure, yet is somehow still more popular. Combine that with a lot of polling that shows the Conservative Party comfortably ahead (though it’s narrowing) in any election race, and Labour’s odds never looked stellar.

Labour’s somewhat muddled stance on Brexit in an election that is absolutely all about Brexit may also be a liability. Labour has said it will renegotiate a new Brexit deal with closer EU ties but will also back another referendum, giving voters the option to remain within the European Union.

Meanwhile, Johnson and the Conservatives are staking their political fortunes on the promise of delivering Brexit by January 31. Other opposition parties, most notably the Liberal Democrats, have carved out a strong position on staying in the EU.

Labour’s platform is trying to please both Brexit supporters and opponents. Amid such polarization, that stance might please no one at all.

Yet Corbyn remains enormously popular with Labour’s activist base, and his ascension to Labour leader has energized the party as he’s moved it leftward, crowding out more centrist figures. He may be the best hope for those who want to figure out a way to stop the UK from leaving the EU — or those who, at the very least, aren’t interested in Johnson’s brand of Brexit.

If British politics in the age of Brexit have proven anything, predictions (or even polling) are not always reliable. A Prime Minister Jeremy Corbyn looks unlikely right now. But nothing is for sure until British voters go to the polls on December 12.

To understand why Corbyn is such a divisive figure, and why his party has struggled to define itself during Brexit, here’s what you need to know about the Labour leader who may never enter 10 Downing Street, but who will shape his party — and Britain’s political future — no matter what.

A brief introduction to Jeremy Corbyn

Corbyn describes himself as a socialist. His politics are a throwback to an older version of Britain’s Labour Party, which embraced government control of parts of the economy and big social welfare programs.

Corbyn was first elected to Parliament in 1983, representing Islington North, a reliable Labour seat in London he’s now held for more than 35 years.

Corbyn came to Parliament in a year that was otherwise horrible for the Labour Party. Its 1983 election manifesto (sort of like a party platform in the US) was one the most left-wing in the party’s history to date. One Labour MP at the time famously called it the “longest suicide note in history” after Conservatives, led by Margaret Thatcher, destroyed Labour that year in one of the largest electoral victories in the postwar era.

That helped begin Labour’s rightward shift to a more moderate, centrist party that is socially liberal but somewhat more fiscally conservative and free-market oriented. That transformation culminated in the election of Tony Blair as Labour leader in 1994. Under Blair, Labour took power in 1997, an era that’s sometimes referred to as “New Labour.”

But Corbyn didn’t shift to the center with the rest of his party. He stayed on the margins, maintaining his ties with other veterans of old Labour and those outside of the party in leftist UK politics.

“He basically spent most of his time opposing the policies of his own party,” Steven Fielding, a professor of political history at the University of Nottingham, told me. Especially when Tony Blair was prime minister, “he was in opposition to everything that was going on,” despite his party being in control of government.

Corbyn, then, was very much an outsider who remained on the backbenches (meaning he never held a ministerial position) for years.

Corbyn’s foreign policy in particular has gotten him into quite a bit of trouble, and it continues to today. He worked closely with Stop the War coalition, which was formed after 9/11 to oppose the intervention in Afghanistan. Not surprisingly, the Stop the War coalition opposed the Iraq War, as did Corbyn. Blair, of course, supported it, a position that would come back to haunt Blair and the Labour Party.

But other positions are harder for Corbyn to justify. He once called NATO a “danger to world peace” and has remained skeptical of many postwar alliances — not unlike US President Donald Trump. He’s ambivalent about the European Union and previously voted against some of the key EU treaties.

Corbyn’s also been sharply critical of Israel, which has fueled allegations of anti-Semitism. In 2009, he famously called the terrorist groups Hamas and Hezbollah “friends.” He supported the Irish Republican Army (IRA), including during the height of the Troubles in the 1980s and 1990s. Campaigning this week in Scotland, a heckler called him a “terrorist” sympathizer.

Corbyn has a lot of political baggage, and for 30 or so years, he was kind of an obscure figure in Labour politics — until 2015, that is.

How Jeremy Corbyn became Labour leader — and why he’s stayed there

Corbyn became Labour leader in 2015 in an extraordinary upset. He started as a 200-to-1 outsider when the contest began but ended up winning 60 percent of the vote from the Labour Party.

His victory was startling at the time, but in retrospect it makes some sense. The era of New Labour had lasted for more than a decade, but Labour lost its majority in 2010, and Conservatives beat them again in 2015.

The dissatisfaction with Labour during this period had a lot to do with its policies under Blair, namely support for the Iraq War. Many British voters also blamed Labour for the 2008 recession, since the party was in charge at the time of the financial market crash.

Voters, particularly younger ones, didn’t love the policies of the Conservatives. The party pursued austerity — in other words, basically lots of spending cuts to social and public services. Other issues, like climate change, also motivated the next generation of voters.

Taken together, voters began to blame the establishment politicians of the past for these failures. Within the Labour Party, some also saw the more moderate Blairites as not all that different from the Conservative politicians.

Corbyn emerged against this backdrop as a politician in his 60s who was untainted by those establishment politics. “What you got was the oldest candidate looking like the freshest and the newest,” David Kogan, author of Protest and Power: The Battle for the Labour Party, told me. It’s not unlike the political rise of Sen. Bernie Sanders in the US.

Corbyn went from impossible odds to looking like the favorite. This was terrifying for most politicians in the party, who saw Corbyn’s ascension as a huge electoral disadvantage, given his leftist politics. At the time, Blair said that with Corbyn as leader, “The party won’t just face defeat but annihilation.”

But Labour’s membership also surged after Corbyn’s victory. The party had less than 200,000 members (people who pay dues) before the 2015 election; in 2018, that number surged to more than 500,000 members, making Labour the largest political party in the UK.

As Kogan explained, Labour’s ranks swelled because Corbyn’s victory brought back those traditional Labour members who had fallen away during the Blair years. It also attracted a new base of young voters, many of whom came of age post-2008 recession and supported Corbyn’s left-wing economic policies, though they were also motivated by those other issues, like climate change.

Corbyn energized the activist base of the Labour Party. But divisions between this coalition of “Corbynistas” and other veterans of the party, specifically lawmakers, did not disappear. In 2016, Corbyn faced a leadership challenge shortly after the June Brexit referendum. Labour lawmakers voted against him in a confidence vote, citing, among other things, his failure to do enough to promote Remain, Labour’s official position in the 2016 referendum.

But Corbyn soundly defeated his challenger in that contest, achieving the party’s backing with a slightly greater margin than in 2015. It showed just how strong Corbyn’s support was among the party base, and how quickly he — and his supporters — had started to reshape the party.

The next test for Corbyn came in the 2017 election. Then-Prime Minister Theresa May called a vote in an attempt to shore up her Brexit mandate. She started out with a 20-point lead and looked likely to deliver another Conservative majority.

Instead, that advantage evaporated. Conservatives lost seats and their majority. Labour increased its number of seats in Parliament by 31. May managed to form a government and retain control by entering into an arrangement with the Democratic Unionist Party, a conservative party in Northern Ireland. But as Brexit unfolded, that control proved to be pretty precarious.

Meanwhile, Corbyn once again defied expectations with Labour’s relative success. That helped undercut some of the doubters.

But not all of them. Those divisions within Labour persist. Though the base of the party has mostly gone all-in for Corbyn, many lawmakers are still in that more moderate mold. Controversies, particularly criticism of Corbyn for his handling of anti-Semitism within the Labour Party, have publicly torn the party apart.

And, of course, there’s the Brexit debate.

Jeremy Corbyn’s big, huge, unavoidable Brexit problem

Corbyn has always been ambivalent about the European Union, which has made him something of an odd fit to be leader during the Brexit debate. Though he voted Remain in 2016, he hasn’t exactly been a full-throated defender of the EU. And he was outright antagonistic at the start of his political career.

Corbyn’s left-wing critique of the EU is a minority view within the party, Eric Shaw, an honorary research fellow in politics at the University of Stirling, told me. But it’s a view some of Corbyn’s associates, who share his ideological bent, support. “The European Union embeds free market principles, embeds corporate power, and membership impedes the capacity of the British government to achieve socialism,” Shaw said, summing up the left-wing critique of the EU.

They’re sometimes called “Lexiteers,” essentially left-wing Brexiteers.

Corbyn voted to leave the European Economic Community, the precursor to the EU, in 1975. As a member of Parliament, he voted against the Maastricht Treaty, which helped form the current version of the EU.

“The whole basis of the Maastricht Treaty is the establishment of a European central bank which is staffed by bankers, independent of national Governments and national economic policies, and whose sole policy is the maintenance of price stability,” Corbyn said at the time, arguing against the treaty in Parliament. “That will undermine any social objective that any Labour Government in the United Kingdom — or any other government — would wish to carry out.”

In 1996, Corbyn blasted the EU bureaucracy as “totally unaccountable to anybody.” Corbyn also opposed the 2008 Lisbon Treaty, which also helped expand the EU.

Fast-forward to the Brexit referendum in 2016: Labour and Corbyn officially supported Remain (so did then-Conservative Prime Minister David Cameron as well as his successor, Theresa May.)

But enough members of his own party saw Corbyn’s campaign for Remain as lackluster at best. His fiercest critics accused him of outright sabotaging the referendum. That helped prompt that 2016 leadership challenge, which Corbyn survived.

But Corbyn’s Brexit problem hasn’t gone away. It’s only gotten worse — for both him and the Labour Party.

Labour’s “fence-sitting” on Brexit is hurting its chances in the 2019 election

In March 2017, the UK Parliament overwhelmingly voted to trigger Article 50, the provision in the EU’s Lisbon Treaty that gives countries the power to withdraw from the bloc. That set off a countdown to a March 2019 Brexit, which, of course, has not happened yet.

At the time, Corbyn and Labour supported triggering Article 50, though some members of his party joined the more than 100 MPs that rebelled against initiating the divorce. This vote happened before the EU and UK ever sat down for serious negotiations, so few knew what kind of Brexit deal then-Prime Minister Theresa May would bring back from Brussels. But the argument at the time was pretty simple: The UK voted to leave, 52 percent to 48 percent, so their representatives had to back the will of the people.

As mentioned above, the UK held general elections in June 2017, a few months later. May wanted to bolster her majority for Brexit negotiations. Labour backed Brexit, but campaigned for a softer version, meaning closer ties with the EU. In that election, May lost her Conservative majority and Labour did much better than expected.

But “better than expected” meant that Labour remained in the opposition, which also meant it didn’t have the power to solve Brexit. Still, Labour frequently joined with the pro-Remain opposition — such as the Scottish National Party and some pro-Remain rebels within the Conservative Party — and helped spoil the Brexit plans of both May and Johnson, forcing all those extensions and blocking a no-deal Brexit.

Corbyn and the Labour Party, then, stood against whatever the Conservative government brought back. At the same time, Labour vacillated on coming up with its own clear position that wasn’t simply anti-May or anti-Johnson or anti-no-deal.

Labour has some reason for this ambiguity on Brexit. Much of his party favor remaining in the European Union, and that includes a huge portion of its base in cities and even those young, grassroots activists who helped get Corbyn elected. But there are Labour seats in constituencies that voted Leave, many in traditional working-class strongholds such as in the north of England.

Though such voters make up a much smaller percentage, they’re still seen as an important part of Labour’s traditional base. (Does this sound familiar, maybe?) And that’s why Labour defended its somewhat amorphous position on Brexit. Unlike Conservatives, who are more explicitly in favor of leaving the EU (though there are pro-Remain people among them), Labour had a much more complicated coalition to represent.

But in trying to please everyone, Labour risks disappointing everyone. If you want to Leave, you have the Conservative Party and the Brexit Party, both of which promise to deliver that. Johnson and the Conservatives have a clear message: Brexit by January 31. The same is true on the other side of the political spectrum. The much smaller Liberal Democrats, as well as the Greens and the Scottish National Party, also have clear messages: no Brexit.

Labour is trying to find a compromise between the two extremes. And in the polarized Brexit era, that might be the worst of all strategies.

In a recent tweet, here’s how Corbyn described Labour’s position: “Secure a credible deal in three months. Put it to the people for the final say, with the option to remain, in six months.”

“That’s our Brexit policy,” he concluded.

The problem with that Brexit policy: it runs into the same problem Labour has had all along: It’s not quite a commitment to Brexit, but it’s also not quite a commitment to stay in the EU.

“It’s a position that is Labour sitting on the fence,” Eunice Goes, a professor of politics at Richmond University in London, told me. “They’re not declaring in favor of Brexit or of remaining” in the EU.

If you’re a voter who’s eager to stay in the European Union, Labour’s policy doesn’t guarantee that. And if you’re a voter who really wants to Leave, Labour’s policy doesn’t guarantee that either.

Corbyn is selling this as, “We’ll give you a final say on Brexit in six months.” But contrast that with the coherent messages of Labour’s competitors, from Johnson and the Conservative (“Get Brexit Done”) to the Liberal Democrats (“Stop Brexit”). Labour’s stance is much more complicated and unclear, and it will also prolong the divorce process even more — taking weeks or months for negotiations, weeks or months for a referendum, and then who knows what comes after that. It’s just a lot.

There are also some logistical problems here. Renegotiating a new deal and getting those extensions also depends on the EU. After May, and after Johnson, will the EU renegotiate with a third prime minister?

Then there’s the issue of holding a second referendum with the option to Remain. If Labour holds such a referendum, will the party — including Corbyn — campaign against the brand-new deal he just renegotiated, and urge people to vote for Remain? Why would the EU go through the exercise of renegotiating a deal if the UK government is going to actively campaign against it?

And then there’s dealing with the fallout of whatever the outcome: a Brexit plan, or voting to Remain, which is likely going to enrage a huge chunk of people in a polarized country.

It’s still not really clear where Corbyn himself stands on the issue of leaving or remaining. Sure, he supports a second referendum — but what outcome does he want? Corbyn has repeatedly dodged this question. During his first debate with Johnson in November, he wouldn’t give a straight answer other than to say a second referendum was the best option.

In a BBC Question Time session with party leaders, Corbyn, when pressed, finally said he would take a “neutral stance” on any referendum — meaning he wouldn’t campaign for Leave or Remain. In other words, he’ll sit on the fence regarding Brexit, right up to the end. What that might mean for his party, especially the pro-Remain lawmakers who really want to remain, is unclear.

Many experts I spoke to think Labour is taking this muddled approach for the wrong reasons. There are Labour districts that voted Leave in 2016, but Labour is still largely a Remain-leaning party. Even in 2017, research showed that most people who voted Labour — even in those Leave-voting districts — voted Remain.

Paul Webb, a professor of politics at the University of Sussex, said that based on analysis of the 2017 election, even in those Leave-voting areas, “The overwhelming majority of people who voted for Labour in those seats were Remainers, and they weren’t Leavers. So they might have been majority Leave seats, but Labour voters in those seats were Remainers.

“In a sense, by worrying too much about these places,” Webb added, “Labour is kind of pandering to its opponents and people who weren’t inclined to vote for the party anyway.”

In other words, Labour’s attempts to retain Leave voters may not be a winning electoral strategy. And even if it was, a soft Brexit/second referendum might not be the option that appeals to them, especially if Brexit is driving the vote. (And in this election, it’s all about Brexit.) And Conservatives are still framing a vote for Labour as a vote to Remain, anyway.

This is where Corbyn’s public skepticism of Europe comes in. Corbyn’s biggest critics say it’s his distaste for the EU that’s ultimately preventing him from taking Labour off the fence and embracing a more explicitly Reman position.

In other words, it really doesn’t matter what Corbyn says or does — he still comes off as a secret Leave supporter. And Labour’s half-baked Brexit stance hasn’t dispelled that impression.

“He actually wants a position going into this election that will allow him to Leave, because that’s what he really wants to do,” Fielding, the University of Nottingham professor, said, though he acknowledged others might disagree with him.

But, he added, that’s why Corbyn is “to-ing and fro-ing and why he’s been so unwilling — on this one issue — to defy Labour members.”

Brexit isn’t Corbyn’s only problem

Brexit may be a huge problem for Labour. But if you hate Brexit, you’re probably not going to cast a vote for a Conservative MP. There’s a risk, though, that Remain-leaning parties like the Liberal Democrats and Greens could split the votes with Labour, allowing a more pro-Brexit candidate to slip through.

The bunch of Remain parties — including the Liberal Democrats, the Greens, and the Welsh party, Plaid Cymru — have pledged to only run the strongest candidate among their parties in certain districts in an effort to avoid any vote-splitting. Some polling has shown that so-called “tactical voting” could boost Labour’s electoral chances, but the party hasn’t signed on. Voters may take it on themselves to vote tactically, or to bet that voting Labour is still the best option to defeat Brexit. But it’s hard to say right now how that will shake out.

And Corbyn is still a problem even beyond Brexit. His political past is still a weakness; voters outside of the core of the Labour Party still see him as a radical figure who espouses extreme positions. His critics are also trying to paint him this way — but many of the policies Labour is promoting in its 2019 manifesto, such as more money for the National Health Service, more affordable housing, and evens some of those the nationalization plans, are pretty popular with the general public.

The anti-Semitism crisis within Labour is likely to be another problem for Corbyn. As mentioned above, Corbyn has been more critical of Israel’s government than most members of his party.

But since his ascension to party leader in 2015, he’s also been accused of showing “poor judgment” on the issue of anti-Semitism.

Some Jewish Labour MPs came under attack from the far right, specifically Jewish women MPs who faced incredible vitriol. But there was also evidence that some Labour Party members were also spewing hateful rhetoric at lawmakers. This turned into a crisis this past spring, when nine Labour MPs left the party. The UK’s Equality and Human Rights Commission launched a formal investigation into the party over those anti-Semitism allegations, a pretty dramatic step.

Corbyn is accused of not having properly condemned the attacks and of allowing this to fester within the party’s ranks. This has damaged “his moral stance as a good man,” Kogan told me. “The accusation of allowing anti-Semitism to take place and not be dealt with, and that’s affected him in his claims to be a different sort of politician.”

The problem isn’t going away, either. The Jewish Chronicle used its front page in early November to call on voters to reject Corbyn. “If this man is chosen as our next prime minister, the message will be stark: that our dismay that he could ever be elevated to a prominent role in British politics, and our fears of where that will lead, are irrelevant,” the newspaper wrote.

The UK’s chief rabbi has also questioned Corbyn’s fitness to be prime minister, weeks into the campaign.

And another former Labour MP, Ian Austin, who left the party over allegations of anti-Semitism earlier this year, said he refused to vote for Corbyn because of his “extremism.” He encouraged voters to select Johnson instead.

Speaking of the current prime minister, contrasting the two further highlights Corbyn’s unpopularity. Johnson is undoubtedly an energetic campaigner, but he’s also a divisive figure who has a lot of baggage. The fact that Corbyn can’t capitalize on Johnson’s weaknesses shows just how broadly he’s disliked.

“I have no doubt that if (as we say here) he was to be run over by a London bus and replaced by the most capable of Labour’s leaders, Keir Starmer, Labour’s ratings would dramatically rise,” Shaw told me, adding that the Conservatives “are praying for Corbyn’s good health.”

A July survey found that the public trusts Johnson — a guy who once got fired for lying — more than Corbyn. Just 21 percent of people have a positive opinion of Corbyn; 61 percent have a negative opinion, according to YouGov. In an August YouGov poll, 48 to 35 percent of voters said Corbyn becoming prime minister would be a worse outcome than a no-deal Brexit.

If you’re thinking, “Sure, but Corbyn didn’t do so bad in 2017!” you’re not wrong — but he’s pretty much been trending downward ever since. His approval has steadily decreased, in some instances hitting truly dismal numbers. His approval rating has ticked up slightly in recent weeks to an average of just 22 percent, according to Howard Clarke, a polling expert at the University of Texas at Dallas. But 22 percent going into a general election is horrendously bad.

As Clarke told me via email, recent polls showed Johnson’s approval rating at around 49 percent — not great, but a heck of a lot better than 22 percent.

Harold Clarke, Ashbel Smith professor of political science at the University of Texas at Dallas School of Economic, Political and Policy Sciences

“That’s what makes this election such a complicated choice for a lot of people,” Amanda Sloat, a senior fellow at the Brookings Institute, told me. “You have voters that are opposed to Brexit, but are very concerned about what a Corbyn government would mean for the country’s social and economic policies.”

Is Labour doomed?

“It’s not looking like a good shot,” Kogan told me about Labour’s chances in the next election.

Johnson and the Conservatives have a strong lead in the polls. Corbyn remains unpopular. Labour’s Brexit policy is still wishy washy. But with less than a month go before Britain votes, it’s probably too soon to call it. Johnson’s lead could evaporate — and Corbyn could do better than expected once again.

Even so, it’s unlikely Labour will win a majority in the 650-seat House of Commons. There have been swings in the polls for Conservatives, with some showing a dramatic lead and others showing a smaller margin of victory, but they’re still ahead in most. Most experts I talked to think Conservatives will win —maybe not with an overwhelming majority, but likely just enough to get Johnson’s Brexit deal through.

Even if that doesn’t happen, an outright Labour majority is still looking difficult to achieve. Instead, the more likely scenario is a hung Parliament, where no one party wins the majority. In this case, it’s possible Labour will do well enough to form some sort of alliance with the Scottish National Party (likely for the price of another Scottish independence referendum), or to at least get the votes of some other pro-Remain parties. Basically, enough anti-Brexit voters will potentially hold their noses for Corbyn to at least try to foil Brexit.

However, experts I talked to agreed that if Labour is defeated outright, Corbyn will almost certainly lose his position as leader. Labour should clean up in these elections. Conservatives have been in charge for 10 years and even they’re promising more spending on things like the National Health Service, in an acknowledgment that the general public is fed up with the Conservatives’ past austerity policies.

Boris Johnson himself is a strange figure in British politics — he’s not all that well-liked nor deeply trusted within the Conservative Party, unable to completely shake the reputation that he’s just out for himself.

If Labour can’t capitalize on this, particularly in this “once-in-a-generation” election, it will be a strong indictment of its leader. But Corbyn’s influence won’t necessarily fade even when he’s gone. He may fail in this election, but the leftward shift he set in motion within Labour could very well outlast him.