As Nikki Haley stepped to the podium Saturday night, the bravado she had embodied after losing in New Hampshire a month earlier was gone. Her expression was somber and, for a moment, she appeared to be edging toward withdrawing from the race for the Republican nomination.

“Our country will fall apart if we make the wrong choices. This has never been about me or my political future. We need to beat Joe Biden in November,” she said, as her audience held its breath.

Finally, she pivoted: “I don’t believe Donald Trump can beat Joe Biden.”

It was a remarkable corrective from Jan. 23, when she spun her 43 percent of New Hampshire’s vote from defeat into a kind of victory and vowed to beat Mr. Trump in her home state of South Carolina.

And though Ms. Haley similarly resolved to stay in the race on Saturday, her fortitude now looked more like stubborn grit and determination than upbeat confidence.

Mr. Trump delivered his own corrective on Saturday night. In New Hampshire, his victory speech had displayed all the grace and decorum of a professional wrestling show, down to mocking Ms. Haley’s dress and taunting her over losing. And he threatened that anyone who donated to her campaign would henceforth be “permanently barred from MAGA,” referring to his “Make America Great Again” movement as if it were one of his private golf clubs.

In Columbia, S.C., Mr. Trump didn’t even mention the name of Ms. Haley, his last major opponent — not exactly gracious, but not insulting either. Instead, he thanked his allies, coming closest to uttering an insult only when he invited Senator Lindsey Graham to say a few words by noting that he was “a little to the left” of the crowd, as his supporters booed their state’s senior senator.

At this point in his political career, no one would mistake Mr. Trump for a unifying force, but in Columbia, he seemed ready to try to at least unite the Republican Party behind his nomination. He did not denigrate Ms. Haley’s voters or threaten her political donors.

Ms. Haley was more realistic about her showing than she was in the Granite State. She said she won “around” 40 percent of the vote, adding that that was “about” what she got in New Hampshire. In that assertion, “about” was doing a lot of work; 40 percent is not 43 percent, and early in the campaign for South Carolina, the super PAC backing her had said she needed to exceed her showing in New Hampshire to prove she was making progress. She did not.

Still, Ms. Haley used her own phrase, “hard truth,” when she leveled with her supporters — even if that hard truth did not conclude with her withdrawal from the presidential race.

“I’m an accountant. I know 40 percent is not 50 percent,” she told the crowd. “But I also know 40 percent is not some tiny group.”

“Today is not the end of our story,” she concluded. That left plenty of options for tomorrow.