Nikki Haley suggested Sunday that she might no longer feel bound by the pledge she made, in order to participate in the Republican primary debates last year, to support the party’s eventual nominee — opening up the possibility that she would not endorse former President Donald J. Trump if he wins the nomination, as he seems increasingly likely to do.

At the same time, she repeated her past assertions that President Biden was a worse option than Mr. Trump, and said that she did not want to engage in “what ifs” or “hypotheticals” premised on her losing the primary. At no point did she rule out endorsing Mr. Trump, even as she said that he had allowed “lawlessness” on Jan. 6 and that she didn’t know whether he would follow the Constitution as president.

The exchange, on NBC News’s “Meet the Press,” began when the host, Kristen Welker, asked whether Ms. Haley had taken the prospect of endorsing Mr. Trump “off the table.”

Ms. Haley hedged, saying, “It’s not anything I think about,” adding: “If you talk about an endorsement, you’re talking about a loss. I don’t think like that.”

After an extended back-and-forth, she described the Republican National Committee pledge she signed last year and said, referring to Mr. Trump’s endorsement of Lara Trump, who is married to his son, Eric, to be a party co-chair, replacing the outgoing chairwoman, Ronna McDaniel: “The R.N.C. is now not the same R.N.C. Now it’s Trump’s daughter-in-law.”

“I think I’ll make what decision I want to make,” she added. “But that’s not something I’m thinking about. And I think that while y’all think about that, I’m looking at the fact that we had thousands of people in Virginia, we’re headed to North Carolina, we’re going to continue to go to Vermont and Maine and all these states to go and show people that there is a path forward.”