Republicans will vote against a key procedural vote Wednesday to proceed with debate on the $1.2 trillion infrastructure bill in the Senate, lead GOP negotiator Rob Portman told CNBC on Wednesday.

“We’re just not ready,” the Ohio senator said in a “Squawk Box” interview.

“The bill is still being negotiated,” Portman said, adding that Republicans have warned for days that “there’s no way we can pull this thing together” in time for the Wednesday vote set by Senate Majority Leader Chuck Schumer, D-N.Y.

“So we’re going to vote no,” Portman said. “We just want time to get it right.”

He predicted that Republicans would be able to support the vote if it is pushed to Monday.

A spokesman for Schumer’s office did not immediately respond to CNBC’s request for comment on Portman’s remarks.

Schumer and other Democratic leaders, with the backing of President Joe Biden, seek to advance the bipartisan infrastructure bill in tandem with a $3.5 trillion budget resolution that is likely to get no Republican support.

The bipartisan plan, which would fund a nationwide update of physical infrastructure systems such as bridges and waterways, would include $579 billion in new spending above a congressional baseline and cost $1.2 trillion over eight years.

The budget resolution, meanwhile, would pour federal money into addressing an array of issues, including climate change and health care.

Facing a tough legislative calendar to pull off this “two-track” feat, Schumer has ratcheted up pressure on the group of senators negotiating the infrastructure bill to finish up with the text of the legislation.

Schumer on Monday evening pushed the legislative process forward — even though the bill has yet to be written — by filing a motion to proceed with a shell bill that he can later swap the infrastructure text into.

On Tuesday, Schumer rejected Republican calls to slow down the process.

Wednesday’s vote, he said on the Senate floor, “is not an attempt to jam anyone,” but rather is “only a signal that the Senate is ready to get the process started.”

To invoke cloture and trigger hours of debate in the Senate, Schumer needs the support of 60 senators in a chamber that is divided 50-50 between Republicans and Democrats.

Portman’s remarks on CNBC suggest that Schumer is unlikely to reach that threshold.

Schumer said Tuesday that if the vote fails, Republicans would “be denying the Senate an opportunity to consider the bipartisan amendment.”

“In order to finish the bill, we first need to agree to start,” he said.