WASHINGTON — President 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. Mr. 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, Mr. 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, Mr. Trump will find it difficult not to shoulder some of the blame.