Representative Elise Stefanik, Republican of New York, was willing to be the team player with the stiff upper lip.

But everyone has their limits.

After a series of public humiliations delivered to her by President Trump — his yanking of her nomination to serve as U.N. ambassador; his Oval Office love fest with New York City Mayor-elect Zohran Mamdani, during which the president undercut her; and the coup de grâce of his refusal to endorse her in the Republican primary for governor — Ms. Stefanik on Friday afternoon announced she’d had enough.

She was done with the governor’s race, for which she had raised more than $12 million from donors who may now be frustrated with her decision to pull out. And done with Congress altogether: She said she would not seek re-election next year.