In what could be the final hours of her campaign, Nikki Haley abandoned a pledge to endorse the GOP nominee and openly wondered about whether Donald Trump would ignore the Constitution.

Why it matters: Haley has yet to win a primary, but she's attracted many of the independent and disaffected GOP voters who will make or break Trump's general election campaign.

The Republican National Committee, whose pledge she signed before last year's debates, "is now not the same RNC," Haley told NBC "Meet the Press" moderator Kristen Welker.

• In the same interview, Haley said only Trump "can answer" what he means by talking about "revenge" and "vindication."
• "[Y]ou always want to think someone will, but I don't know," Haley told NBC when asked whether Trump would follow the Constitution.
• Trump plans to replace the RNC's top leadership with a triumvirate that includes his top campaign adviser and his daughter-in-law.

Zoom in: Trump piled up more delegates on Saturday after winning caucuses in Missouri, Idaho and Michigan.

• Haley's best shot to win a GOP primary is in D.C., where voting ends on Sunday.

What's next: Haley has consistently delayed questions about the future until after Super Tuesday. That rain check comes due Wednesday.

• The last Trump runner-up in a GOP primary was former Ohio Gov. John Kasich in 2016, who cast a protest vote for the late Sen. John McCain that November and spoke at the Democratic National Convention in 2020.
• "I'm not anti-Trump," Haley told Politico on Friday. "Look, if I was doing that, I would be Chris Christie."