WASHINGTON — President Trump, who has branded himself for decades as a skilled deal-maker, told congressional Republicans Tuesday that “failure is not an option’’ when it comes to the controversial health reform bill, and reportedly warned lawmakers he would “come after you’’ if they didn’t support it.

According to reports from those in the closed-door meeting, Trump issued vague threats to the skeptical group of conservatives ahead of the House floor vote, which is scheduled for Thursday. Though it was unclear whether the comments were made in jest, he told lawmakers that those who buck the party line could face primary challengers or his own wrath.

‘‘If you don’t pass the bill, there could be political costs,’’ Trump said to the group, according to Representative Walter Jones of North Carolina.

The president’s visit to Capitol Hill underscored the high stakes involved as Trump and Republicans grapple with ideological divides within their own party in a bid to fulfill a core campaign promise. House Speaker Paul Ryan and Trump are trying to engineer the necessary 216 yes votes from Republicans, but by most counts they were still coming up short Tuesday. And even if they can win passage in the House, a number of Republicans in the Senate have raised objections, promising even more hurdles.

Trump signaled Monday that he is prepared to use a big share of his political capital among conservatives to push the bill. At another point during Trump’s meeting with the House GOP, according to those in the room, Trump called on Representative Mark Meadows, the chairman of the hard-line conservative group known as the House Freedom Caucus, whose endorsement is critical for the bill’s passage.

Trump reportedly asked Meadows to stand up.

“I’m going to come after you, but I know I won’t have to, because I know you’ll vote ‘yes,’ ’’ the president said. “Honestly, a loss is not acceptable, folks.’’

The president’s tone spoke to the tension-filled moment in which Republicans find themselves. After more than six years of vowing to “repeal and replace’’ former president Barack Obama’s Affordable Care Act, the hallmark piece of domestic legislation informally known as Obamacare, the GOP is finding the realities of governance to be a more difficult task.

Another sign of the difficulty: Republicans on Monday night announced a flurry of late changes to their American Health Care Act.

The new, revised bill creates a $75 billion pool aimed at curbing health care costs for older Americans, accelerates the start of new tax breaks for America’s highest earners, and gives individual states the options to drastically alter Medicaid through work requirements or funding changes. Most of these measures are decried by health care experts but preferred by conservative lawmakers.

Sean Spicer, the White House press secretary, said Trump endorsed the changes and hopes they lead to the majority necessary to pass the bill in the House.

“A lot of the measures that have been changed and tweaked and updated have assuaged members that had concerns or that wanted to see some additional tightening,’’ Spicer said. “But keep in mind, if you are a conservative, who has been fighting for ‘repeal and replace,’ this is your chance.’’

But while Trump, Ryan, and Senate majority leader Mitch McConnell are united in their support of the conservative health care overhaul, other Republicans are openly defying the party line, even after meeting with Trump.

Representative Jim Jordan, a member of the Freedom Caucus, said he doubts the bill has enough votes to pass.

“The president’s great; the bill’s still bad,’’ Jordan said.

Meadows, the Freedom Caucus chairman who was called out by the president, said he was unmoved by the meeting.

“I’m still a ‘no,’ ’’ he said. “I’ve had no indication that any of my Freedom Caucus colleagues [there are 25 members] have switched their votes.’’

Trump told reporters that he was optimistic about Thursday’s vote and said he was encouraged by the changes that were introduced earlier in the week. However, as has been the case throughout the weeks-long debate about health care, the president declined to speak in specifics and largely characterized health care reform as a mere prerequisite for other parts of his first-year agenda, including tax and immigration policy.

“We’re [going to] have a real winner,’’ Trump told reporters after the meeting. “There are going to be adjustments, but I think we’ll get the vote on Thursday.’’

But according to both nonpartisan policy analysts and even some from conservative think tanks, the first round of adjustments probably made the health care bill less palatable to some lawmakers and policy experts.

The first version of the bill would result in 24 million people losing insurance by 2026, according to the Congressional Budget Office initial estimates. It would also reduce deficits by $337 billion over 10 years, though much of that reduction would shift to the working poor who could not afford to buy insurance without government subsidies.

The revised bill expands tax credits aimed at controlling health care costs for elderly citizens, but the new amendments also give states the ability to impose work requirements for childless, able-bodied Medicaid recipients and shifts funding mechanisms to a block grant program, which would cap the amount of money available for benefits. Both these provisions are opposed by most health care analysts.

Hannah Katch, a senior policy analyst at the liberal-leaning Center on Budget and Policy Priorities, said shifting to capped block grants instead of open-ended entitlements would give states an incentive to force individuals off Medicaid rolls. Additionally, work requirements have not been empirically proved to work, she said.

“There is no way to look at this amendment and not see it as taking away coverage from people who have no where else to turn,’’ she said.

Katch provided 2017 data from the Kaiser Family Foundation which showed that, of the small minority of Medicaid recipients who are currently not working, most reported a major impediment to work, including caring for a sick family member or being in school.

Even some Republican thinkers, including Robert Rector of the conservative Heritage Foundation and an architect of the work requirements provision in the 1996 welfare reform law, has written papers in opposition to a similar plank in Medicaid.

In a piece written last week, Rector said, “Work requirements for medical services would be almost impossible to administer and enforce.’’

What the amendments do underscore, said Matthew Fiedler, a fellow in the Center for Health Policy at the Brookings Institution, an independent think tank, is the difficulty Republican leadership faces in satisfying the competing wings of ideology: the hard-line conservatives who want to totally undo government entitlement programs and the moderate Republicans who are worried about constituents losing health coverage.

“Leadership will work hard to bridge those two factions,’’ Fiedler said. “But it’s going to be difficult.’’

His words harkened back to a passage in President Trump’s “Art of the Deal,’’ the best-selling book that thrust Trump into the national spotlight in 1987.

In a passage where Trump outlines the high stakes of his negotiating tactics, he says that, in the end, people only remember the person who get results.

“You can’t con people, at least not for long,’’ Trump wrote. “If you don’t deliver the goods, people will eventually catch on.’’

Material from the Associated Press was used in this report. Astead W. Herndon can be reached at astead.herndon@globe.com. Follow him on Twitter @AsteadWH