On Fox News over the weekend, the conservative columnist Charles Krauthammer said Republicans had basically given up on arguing for a more purely free-market health care system.

“They have sort of accepted the fact that the electorate sees health care as not just any commodity, like purchasing a steak or a car,” Mr. Krauthammer said. “It’s something now people have a sense the government ought to guarantee.”

The complexity of unraveling the Affordable Care Act became evident to Republicans even before Mr. Trump was sworn in, as they started planning their legislative agenda for his first 100 days. Led by Speaker Paul D. Ryan, the party assumed that a repeal would be one of the first items — if not the first — on its calendar.

Then Mr. Trump, who had campaigned on preserving programs, like Social Security, Medicare and Medicaid, that his party had aimed at in the past, said on Twitter less than two weeks before Inauguration Day that a replacement must accompany a repeal — much to the surprise of Mr. Ryan and the party leadership on Capitol Hill.

To the dismay of many conservatives, the promise to repeal had morphed into a pledge to replace. Even worse, some Republicans started talking about another dreaded R word: repair.

Mr. Ryan, speaking on Sunday on ABC News, used language not ordinarily heard from free-market, anti-entitlement conservatives like himself. The speaker, perhaps his party’s most vocal proponent of bringing down the cost of entitlements, argued for the House bill not on the basis of how much money it would save — in part because he rushed the vote before a proper accounting could be completed — but how many people would be left covered.

He called Republicans’ efforts a “rescue mission” to provide affordable health insurance, “especially and including to people with pre-existing conditions.”