Mick Mulvaney is trying to achieve as acting White House chief of staff what he never could as a conservative firebrand in Congress.

Mulvaney this week helped persuade President Trump to get behind a legal effort aimed at striking down the Affordable Care Act over the objections of some in the administration and Republican leadership on Capitol Hill.

His pitch came during scheduled “policy time” with Trump on Monday and spanned several meetings throughout the day. It was met with resistance from some on the president’s legal team and his Justice Department, as well as with skepticism from Vice President Pence, who favors overturning President Barack Obama’s namesake health-care law but only if Republicans are ready with an alternative, according to White House officials familiar with the discussions who spoke on the condition of anonymity to describe the private talks.

But Trump — fresh off a victory lap following the conclusion of special counsel Robert S. Mueller III’s Russia investigation — agreed with Mulvaney and was eager to forge ahead into dismantling his predecessor’s health law.

“The Republican Party will soon be known as the party of health care,” the president enthused while walking into a lunch of Republican senators Tuesday. He seemed to try to justify his administration’s unexpected decision, telling reporters in the Oval Office on Wednesday that “if the Supreme Court rules that Obamacare is out, we’ll have a plan that is far better than Obamacare.”

Mulvaney and his allies have told Trump that joining a lawsuit to overturn the ACA will help him fulfill a campaign promise and could help lead to his reelection, but congressional Republicans worry he’s sent the president on a suicide mission. While Republicans are united in their opposition to Obama’s signature health-care law, they remain divided on how to replace it, and Democrats are eager to exploit this tension while making health care a centerpiece of the 2020 campaign.

The behind-the-scenes role played by Mulvaney — who in Congress was a member of the hard-right Freedom Caucus and earned a reputation for frustrating Republican leadership — highlights the way he has operated as a top aide to Trump, first as budget director and now as acting chief of staff.

If Trump is well-known within the White House for having little interest in both policy and nuance, Mulvaney seems to specialize in it. But the acting chief of staff has also sought to frame his long-held views in a way that won’t undermine the president. This has allowed Mulvaney to use his proximity to power to directly shape major White House policy proposals that echo his priorities during a congressional career spent more in shouting from the sidelines than in rooms where deals were made.

He used his budget office perch to craft spending plans that drastically reduced funding for programs such as education, environmental protection and housing. Earlier this year, following a partial government shutdown he supported, it was Mulvaney who helped aggressively engineer the controversial emergency declaration plan to fund large sections of a border wall without congressional approval — and dubbed it “D-Day,” White House officials said. It was a move that deeply frustrated many Senate Republicans, but Mulvaney told the president that senators wouldn’t override him. And now he has pushed Trump into a health-care fight many in the party are eager to avoid. 

“The greatest political liability one can accrue is advocating for the disruption in coverage for Americans who are currently pleased with their own health care,” said Josh Holmes, a former senior adviser to Senate Majority Leader Mitch McConnell (R-Ky.). “What’s happened in the last six months is the Democrats have taken the health-care issues and have walked to the precipice of the cliff and are ready to drop off. The only thing that’s saving them is a Republican grabbing them by the collar and jumping off instead.”

Rep. Mark Meadows (R-N.C.), who chairs the Freedom Caucus and is close with Mulvaney, said the acting chief is taking the right approach. “The 2020 elections will be more about domestic policy than they will be about foreign policy,” Meadows said. “It’s Mick Mulvaney’s sweet spot.”

In a new court filing Monday night, the Justice Department argued that the Affordable Care Act, also known as Obamacare, should be thrown out in its entirety. The filing was made with the U.S. Court of Appeals for the 5th Circuit in New Orleans, where an appeal is pending in a case brought by Republican state attorneys general challenging the law’s constitutionality. A federal judge in Texas ruled in December that the entire law is invalid, in an opinion that went considerably further than the administration’s position at the time.

Before Monday’s filing, the Justice Department argued that there were grounds only to strike down the law’s consumer protections, including those for people with preexisting health conditions, but that the rest should be kept intact. Now the administration wants the whole law thrown out.

Politico first reported Mulvaney’s role in pushing Trump to support invalidating Obamacare. 

Mulvaney is proving to be a far different chief of staff than his predecessors. Reince Priebus, who first held the job, spent much of his time careening around the West Wing — trying to manage his presidential charge and the West Wing’s feuding factions. John Kelly, Trump’s second chief of staff, was a strict gatekeeper who worked to limit the president’s inner circle.

“What would surprise people is that the Freedom Caucus member who went to OMB and is now chief of staff is willing to evaluate things without making his opinions be a part of any calculation,” Meadows said. “The other [thing] is Mick Mulvaney has probably the second most powerful position in Washington, D.C., and yet he allows other people access to the president and doesn’t feel challenged by that.” 

Mulvaney has adopted a more relaxed approach, despite having held three different posts in the administration — at one point, he was acting director of the Consumer Financial Protection Bureau — and at times holding two roles simultaneously. 

White House officials say Mulvaney is generally well-liked within the West Wing, allowing robust debate and empowering various advisers and officials. He helped foster his personal relationship with Trump over golf — and was on the course with the president as recently as Sunday, where the topic of health care also came up. 

“Mick’s approach is hands-off but not hands-free,” said White House counselor Kellyanne Conway. “He is involved in every policy discussion, presidential decision-making exercise, and he and his team make sure the president is fully briefed.”

Mulvaney aides have deliberately worked to keep his profile low, arguing that Trump often sours on advisers when he reads stories that say they are controlling, shaping or trying to influence him. Mulvaney declined to be interviewed for this article. 

He asks the president detailed questions about his daily calendar, knowing that Trump does not like to be over-scheduled and likes to have free time, and adheres to what Trump wants. He has also taken it upon himself to try to serve as Trump’s inside-the-Beltway fixer, familiarizing himself with as many rules and laws as possible to help his boss avoid stumbling blocks.

Earlier this month, when Trump unleashed 52 frenzied tweets in just 34 hours, Mulvaney was on vacation in Las Vegas. He has told other White House aides that he only worries about Trump’s tweets if they threaten a legislative priority — such as alienating a needed vote — or if they announce policy or personnel.

Mulvaney has also described a steep learning curve on foreign policy, and told others how surreal it was to meet North Korean leader Kim Jong Un at the Hanoi summit last month.

His health-care maneuvering was met with dismay from many in his party. House Minority Leader Kevin McCarthy (R-Calif.), for instance, has urged Trump to hold off on pushing for the courts to overturn Obamacare, a private pitch first reported by Axios. A Republican strategist in frequent touch with the White House said some in the administration were frustrated with Mulvaney for his “ham-handed move,” describing Mulvaney as abiding by “Freedom Caucus and club for dopes rules.”

Mulvaney has been aligned with a broad coalition of conservative groups that have worked with the Republican attorneys general who brought the ACA lawsuit and have urged that the president adopt a harder legal line, according to a former member of Trump’s domestic policy transition team and steering committee member of the Conservative Action Project. Others, including Health and Human Services Secretary Alex Azar and Attorney General William P. Barr, have been more aligned with McConnell, who has feared that any wholesale rejection of the 2010 health-care law would exert pressure on Congress to reopen debate about how to replace the ACA, according to the individual, who spoke about internal conversations on the condition of anonymity.

“Alex and, I think, Barr, have the more reserved positions,” the individual said. “The president netted out with the harder-line approach.”

Trump himself has not articulated his plan for health care, and urged members of Congress to write one. In his meeting Tuesday on Capitol Hill, he explained to senators that health care was the party’s main vulnerability because they had “owned” the economy and the border, officials with knowledge of the meeting said. He told them he decided in the motorcade ride over that his new slogan would link Republicans to being the party of health care.

Mulvaney’s defenders say that on health care, he is simply helping Trump achieve his policy objectives. When the Texas ruling was first announced, for instance, Trump tweeted that the decision was “great news for America!” 

Mulvaney’s budgets as OMB director have also prioritized the president’s goals over some of those Mulvaney himself advocated for as a fiery and conservative lawmaker. His fiscal plans have jacked up spending for military programs, a priority for Trump, and stopped short of imposing major structural changes to Medicare because Trump ordered it. Trump, however, grew angry last year when he learned Mulvaney was behind a budget request for the wall that only requested $1.6 billion.

If Mulvaney, who wears a boot on his right foot for an Achilles heel injury, struggled to transition from a conservative mischief maker who enjoyed needling his party’s leadership to a deputy in the Trump administration, he has shown few outward signs. In a closed-door speech to donors last year, Mulvaney argued that Republicans should support Trump even if they find his style distasteful, according to a recording of the event obtained by The Washington Post. 

He cited the administration’s handling of religious freedom cases and said there were many more examples.

Still, he added, “It’s not sexy.”

Alice Crites and Amy Goldstein contributed to this report.