WASHINGTON — Mitt Romney did not vote for Donald J. Trump in 2016. Representative Martha McSally of Arizona may not have, either, but she will not say. And Senator Dean Heller of Nevada now insists that he did cast his ballot for Mr. Trump, but for many months, he would not reveal his vote.

Senator Bob Corker supported Mr. Trump, but seemed to regret it last year when he concluded that the country had deposited an unruly toddler in the Oval Office.

Yet as these Republicans pursue a Senate run this year — or in the case of Mr. Corker, reconsiders one — they are essentially making peace with a president they once shunned. Their hopes for a détente with Mr. Trump, who effectively staged a hostile takeover of a party he joined only in 2012, reflect the realization that rank-and-file Republicans have come to embrace the president.

There is little appetite on the right for Trump skeptics in the halls of Congress.

“To the activists, those who vote consistently in Republican primaries, it’s very much Trump’s party,” said Senator Jeff Flake of Arizona, who effectively decided against running for re-election because he did not want to accommodate such voters.