WASHINGTON – President Donald Trump, after a halting start, is now marshaling the full power of his office to win over holdout conservatives and waffling senators to support the House Republicans' replacement for the Affordable Care Act.

There are East Room meetings, evening dinners and sumptuous lunches — even a White House bowling soiree. Trump is deploying the salesman tactics he sharpened over several decades in New York real estate. His pitch: He is fully behind the bill to scotch President Barack Obama's signature domestic achievement, but he is open to negotiations on the details.

In so doing, Trump is plunging personally into his first major legislative fight, getting behind a bill that has been denounced by many health care providers and scorned by his base on the right. If it fails, Trump will find it difficult not to shoulder some of the blame.

"He understands the power he has as president to drive the legislative process," said Rep. Patrick T. McHenry, R-N.C., a top House vote counter who was part of a meeting with Trump in the East Room on Tuesday.

"He made it clear that this is his priority, that it has to get done, and he made clear that he has to get it through before he moves on tax reform," McHenry added.

The bill represents an opening for an administration that has been mired in infighting and controversy over an early executive action on immigration. And it will allow Trump to make good on a pledge he made in rally after rally in 2016 to replace Obama's law, which he called a "disaster."

And it has momentum. On Thursday, two key House committees approved the legislation, which would undo the Affordable Care Act and replace it with a more modest system of tax credits and a rollback of Obama's Medicaid expansion. Party-line votes by the House Energy and Commerce and Ways and Means Committees sent the measure to the House Budget Committee for consideration next week before a final House vote that Speaker Paul Ryan plans for later this month.

"Today marks the beginning of the end of Obamacare," Rep. Steve Scalise of Louisiana, the majority whip, declared after the votes.

The risks for Trump are high. His initial foray into the debate was a declaration that nobody should lose insurance coverage with a replacement bill — a standard that is likely to be impossible to meet. When House Republicans finally unveiled the legislation Monday night, he declared on Twitter, "Our wonderful new Healthcare Bill is now out for review and negotiation" — hardly a hard line.

Already, debate on the measure is taking far longer than Trump had hoped, delaying his push to cut taxes, rewrite the tax code and secure a sizable new infrastructure program. If his health care push fails, the reverberations will affect those other measures.

For all of Trump's characteristic bluster, the self-described king of the deal is treading gingerly on the actual policies in the bill. After members of the hard-line House Freedom Caucus complained that they were not being listened to by the House Republican leadership, Trump sought to bring them along by listening to their concerns before dictating his desires, his advisers say.

For now, those advisers say, Trump is in listening mode. He had dinner Wednesday with Sen. Ted Cruz of Texas, who is leery of the House bill. He got an earful from conservative opponents of the bill when he met at the White House with representatives of the Heritage Foundation and Americans for Prosperity on Wednesday night.

On Thursday afternoon, the White House director of social media, Dan Scavino Jr., posted a photo on Twitter of the president sitting around a table at a meeting that Scavino said was budget-related. But among those at the table with the president were Rep. Mark Meadows of North Carolina, the chairman of the Freedom Caucus, and Rep. Jim Jordan of Ohio, two of the biggest obstacles to any health care bill deemed insufficiently thorough in obliterating the Affordable Care Act.

The president has not spent enormous time negotiating specific aspects of the bill, people who have spoken with him say. But some of his advisers have been critical of the House Republican Conference, led by Ryan, for not doing more to bring along conservative members. The meeting at the White House with leaders of conservative groups was an effort to remedy that, Trump's aides said.

And in a sign of the White House still grappling with how tightly it wants to embrace the current bill, Vice President Mike Pence will appear instead of Trump on a trip to Louisville, Kentucky, this weekend. On Wednesday, Trump will hold a campaign rally in Nashville, Tennessee, where he is also expected to barnstorm for the repeal of the Affordable Care Act.

"The president will be visiting several cities over the next coming weeks to engage the American people on the need to repeal and replace," Sean Spicer, the White House press secretary, said Thursday.

Last week, Trump's aides grew frustrated when the House Republican leadership bluntly told them that the president would need to use his political capital to bring people along. The tensions fall squarely in the purview of Reince Priebus, Trump's chief of staff, who is close to Ryan and who some of the president's advisers fear has divided loyalties. Trump vented his frustrations with Priebus on March 3 over how much work remained toward preparing for the health bill rollout.

Trump's advisers mostly welcomed the discussion of the bill as a reprieve from the controversy over Trump's post on Twitter saying, without evidence, that he had information that Obama had "tapped" Trump's phones at Trump Tower during the campaign.

Those advisers are also aware that the rollout of the plan has been bumpy, with only deeply limited spade work done by the House Republican Conference to shore up outside support beforehand. Nudged by frustrations from the West Wing, Ryan on Thursday conducted a PowerPoint presentation with members of the news media to explain the three phases planned for repealing and replacing the ACA.

But White House advisers are well aware that they are saddled with the bill now. At the same time, they describe Trump as walking lightly — by his standards, at least.

The vice president's trip to Kentucky will bring Pence to a state that is being treated as ground zero in the repeal fight. Kentucky's junior senator, Rand Paul, is the bill's most prominent Republican critic. Its former governor, Steve Beshear, became a Democratic hero for successfully implementing the health care law in the deep red state, but Republicans took full control of its statehouse in elections last year despite the Democrats' strong support for the Affordable Care Act.

There is some daylight between the House Republican leaders and the White House on how much change the bill can absorb. Rep. Joe L. Barton, R-Texas, offered an amendment on Thursday that would have moved the health care bill in a conservative direction, reducing federal funds for the Affordable Care Act's expansion of Medicaid at the end of 2017, two years earlier than under the legislation drafted by House Republican leaders.

Barton withdrew the amendment but hinted that it could reappear when the bill hits the House floor. The proposal was supported by two influential conservative groups, the Republican Study Committee and the House Freedom Caucus — and, he said, "the Trump administration is open to it." Indeed, the White House has begun pushing for a 2017 end to the Medicaid expansion, a senior Trump adviser confirmed — a move that risks pushing away moderates across Congress.

Trump also wants the Republicans' health care bill to inject more consumer choice into the process of selecting plans, said someone familiar with the president's thinking, as well as the elimination of state-by-state insurance options. Such changes are impossible under the budget rules that Republicans are using to avoid a Democratic filibuster in the Senate.

McHenry said Trump talked in the meeting this week about how he had performed in the districts of lawmakers whose votes will be necessary.

The criticism of the bill from conservative groups grew so hostile so quickly that it surprised even Trump. So Trump moved to use the trappings of the presidency to woo them.

Initially, the group was told it would see the president in the Roosevelt Room. But after the group's members waited there for a short while, an aide entered and said, "The president would like to see you in the Oval Office."

Even so, it quickly became evident that the objections the activists had with the bill could not be washed away with the awe of the Oval Office. The president told them he did not appreciate the attacks on the proposal as "Obamacare lite" or something that fell short of a repeal. That kind of talk, he warned them, could be detrimental to their shared cause of gutting the Affordable Care Act.