Conservatives were taken aback. Senator Ben Sasse, a Republican from Nebraska who opposes Mr. Trump, said in a series of posts on Twitter that the billionaire businessman appeared to embrace most of the health law and wondered what kind of Supreme Court justices he would appoint if elected. The legality of the mandate, and the government’s power to impose fines on people who ignore it, was central to the Supreme Court decision that upheld the law in 2012…

Rush Limbaugh, the conservative radio host who has been a defender of Mr. Trump in many instances, was also incensed. And he took issue with Mr. Trump’s suggestion that other Republicans are not disturbed by the idea of people dying in the street.

“You can’t talk about repealing Obamacare and like the mandate,” Mr. Limbaugh said during his show on Friday.

In the face of that backlash, Mr. Trump fired back on Twitter that he had been misunderstood. He said he only liked the provision in the law that requires insurers to provide coverage for people who are already ill. He then promised that he intended to repeal the entire piece of legislation, including the mandate.