Pelosi and Schumer meet with Biden

House Republican leaders are launching an all-out campaign to sink a bipartisan infrastructure bill, as Democratic leaders struggle to unite their caucus around the legislation ahead of a high-stakes floor vote on Thursday.

While the $1.2 trillion infrastructure package contains popular items widely supported by both parties — and earned the backing of 19 Republicans in the Senate — GOP leaders in the House want to ensure that Republicans won’t be the reason the bill gets over the finish line, and have begun to crank up the pressure on their members.

​​Both House Minority Leader Kevin McCarthy and House Minority Whip Steve Scalise have been making personal calls to members and talking to members on the floor, according to GOP sources. And while Republican leaders are not threatening members who back the bill, they are being forceful with their pitches, those sources said.

“Our argument is that infrastructure is a gateway drug to reconciliation,” a source familiar with the whip operation said.

The source expects between a dozen and 20 House Republicans will vote “yes” on the legislation, but said it wouldn’t be enough to offset the mass defections progressives are threatening if the bill comes to the floor without a deal on legislation to expand the social safety net through reconciliation.

“There won’t be enough Republicans to carry this if there is widespread opposition,” the person said. 

One Republican member said the whipping operation was “pretty intense.” Another Republican described the effort as an “8 out of 10.” And a third House Republican said “we’re very serious about it.”

While GOP leaders have acknowledged that there will be some Republicans who cross party lines, Scalise said at a press conference earlier this week that they will “work to keep that number as low as we possibly can.”

The scramble to limit GOP defections underscores just how high the stakes are for both parties. President Biden’s domestic agenda is on the verge of imploding as Democratic leaders struggle to unite the warring factions inside their party. And Republicans — keenly aware that the passage of infrastructure and reconciliation may be Democrats’ best hope for keeping their majorities next year — are eager to keep the spotlight on the disarray across the aisle.

CNN’s Daniella Diaz and Ryan Nobles contributed reporting to this post.