WASHINGTON — President Trump offered a closing argument on Tuesday to on-the-fence lawmakers, warning House Republicans that they risked losing re-election next year if they failed to get behind legislation to repeal and replace the Affordable Care Act.
Mr. Trump’s warning, delivered in a closed-door meeting at the Capitol on Tuesday morning, came as House leaders were trying to pin down a majority to pass their repeal legislation, which is set for a floor vote on Thursday.
Mr. Trump told lawmakers that many of them would lose their seats in next year’s midterm elections if the repeal effort failed.
“He warned us that there are consequences if we don’t come together, for us as a party and also for individuals,” said Representative Richard Hudson, Republican of North Carolina. “He wasn’t threatening in any way. He was just giving us a pretty clear warning.”
Republican leaders have pointed to Mr. Trump’s advocacy for the House bill — though less than rock-solid at times — as they have struggled to gain enough support to push their measure through the House. But conservative lawmakers who are skeptical of the House bill could be hesitant to vote against it if such a vote might prompt a public shaming from the president.
“He made it very clear he’s all-in on this legislation,” said Representative Kevin Brady, the Texas Republican who is chairman of the Ways and Means Committee. “This is a historic moment and a historic promise for Republicans to deliver on this Thursday.”
Speaker Paul D. Ryan was upbeat. “The president just came here and knocked the ball out of the park,” Mr. Ryan said. “He hit the cover off the ball.”
On the eve of Mr. Trump’s visit to Capitol Hill, House leaders released a set of revisions to their bill, including a provision sought by Republicans from upstate New York that would shift Medicaid costs from counties to the state government.
The changes also included provisions to allow states to impose a work requirement for individual able-bodied Medicaid beneficiaries, and to allow states to choose a lump-sum block grant to fund Medicaid.
Both of those revisions were meant to win over conservatives, and Mr. Ryan presented the health bill on Tuesday as an improved product that had been refined as much as possible to reflect lawmakers’ concerns — and now needed to be approved so that lawmakers could fulfill their promise to repeal the health law.
“In this day and age, and in this business, in politics, if you get 85 percent of what you want, that’s pretty darn good,” Mr. Ryan told reporters.
But even with the changes, passage of the House bill remained far from assured, with rank-and-file members still voicing dissent.
Representative Ted Budd, a freshman Republican from North Carolina, said on Tuesday that he did not support the bill, which he said: “does not provide the relief that North Carolina families need from high premiums.”
Representative Leonard Lance, Republican of New Jersey, expressed disappointment with the legislation.
“I campaigned in support of a ‘repeal and replace’ bill that would make health care more affordable and accessible and provide a smooth transition to those who were forced into Obamacare through no fault of their own,” Mr. Lance said. “The bill, as currently drafted, does none of these things.”
Michael A. Needham, the chief executive of Heritage Action, a conservative group, said without “additional changes,” his organization would press lawmakers to vote no. In a post on Twitter, Mr. Needham said the group would factor the vote into its annual scorecard for members of Congress, a crucial barometer for conservative Republicans.
Mr. Trump appeared before lawmakers on Tuesday to offer a different message — one laced with possible electoral consequences.
Representative Chris Collins, Republican of New York, said the president was “very direct” in discussing the “political repercussions” of the vote, saying Republicans would pick up seats if they delivered on their promise to repeal the Affordable Care Act, but could lose seats if they failed.
Likewise, Representative Harold Rogers, Republican of Kentucky, said Mr. Trump warned that “it could be a political liability” if Republicans voted against the bill.
Mr. Trump also singled out Representative Mark Meadows, Republican of North Carolina and the chairman of the House Freedom Caucus, a group of conservatives that has resisted the House plan.
Mr. Rogers said Mr. Trump told Mr. Meadows that he was coming after him. The president “was kidding around — I think,” Mr. Rogers said.
Though Mr. Trump had called him out by name, Mr. Meadows said he did not feel “threatened.”
“I certainly still think the president is the best guy to bring this home and close this deal out,” Mr. Meadows said. “Hopefully, we’ll be able to do that, but if everyone’s entrenched at this particular point, it’s going to be a tough 48 hours.”