Since he was elected, President Trump’s relationships with Republican lawmakers on Capitol Hill have mostly fallen into one of two categories: the unbreakable bond with his most ardent followers, who defend him at all costs, and the tenuous, strained alliance with the rest, who share his agenda but often cringe privately at his language and tactics.

Neither group is particularly well suited for the chore of trying to persuade Mr. Trump, who refuses to concede the election, that it is time to step aside — or at the very least, to stop spreading claims about the integrity of the nation’s elections that are contrary to considerable evidence. And there is little chance that Mr. Trump, who has been perplexed and sometimes enraged by the Republican institutionalists who might normally be expected to play such a role, would listen if they did…

“It’s very difficult for Republicans whose leader got 71 million votes, the most by any Republican standard-bearer ever, to simply just turn their backs on him,” Mr. Naftali said. “The issue is now not so much Trump as loyalty to Trumpism. And I think that’s why you see the contortions now. If you’re a Republican and you get this wrong, you’re going to be primaried out.”