Once Critics of Trump, These Republicans Are Now Playing by His Rules

There was a time when Nikki Haley thought an “unstable and unhinged” person should not be president. But that was February. Now she says she will vote for Donald J. Trump — just three months after warning that he would be “an unsafe president.”

She is hardly the first losing candidate to reverse course and support the rival who beat her for a party nomination. Flip-flopping has a long if uninspiring history in American presidential politics. But rarely have the flip-flops been as stark and head-snapping as those prompted by Mr. Trump.

Ever since he vaulted to the leadership of the Republican Party eight years ago, the same Republicans who once deemed him a “kook,” a “pathological liar” and a “delusional narcissist” nonetheless have come around to endorse handing him the nuclear codes. Even many of those who called him out for trying to overturn an election that he lost are now willing to entrust him again with the future of American democracy.

Given Mr. Trump’s enduring popularity with the party base and willingness to punish apostates, the lesson of recent years has been that nearly everyone hoping for a future in Republican politics feels the need to swallow any past criticism and fall in line. Even some Republicans no longer aspiring to hold public office have buried their apprehensions to stay with the choice of the party’s voters.

The disparity between their onetime judgments and their eventual public postures has been scorned by none other than Ms. Haley — that is, Ms. Haley, the Trump critic, before she became Ms. Haley, the Trump voter.

“Many of the same politicians who now publicly embrace Trump privately dread him,” she said while competing with him for the Republican nomination this year. “They know what a disaster