Nikki Haley Endorsed by Gov. Chris Sununu of New Hampshire

Gov. Chris Sununu of New Hampshire endorsed Nikki Haley for the Republican presidential nomination at a campaign event Tuesday evening, casting her as a fresh face for the party who could take on the elites in Washington and move the nation past the “nonsense and drama” of former President Donald J. Trump.

“We are all in for Nikki Haley,” Mr. Sununu said to loud cheers at a ski area in Manchester, adding that her momentum was “real” and “tangible” and that her poll numbers and ground game have been “absolutely unbelievable.”

Pacing in the middle of the audience, Ms. Haley called it “a great night in New Hampshire.” “It doesn’t get any better than this — to go and get endorsed by the ‘Live Free or Die’ governor is about as rock-solid of an endorsement as we could hope for.”

The endorsement is a significant victory for Ms. Haley, who is trying to establish herself over Gov. Ron DeSantis of Florida as the main alternative to Mr. Trump and has gained ground in New Hampshire polling in the past month.

Mr. Sununu, a Trump critic who is serving his fourth and last two-year term as governor, was re-elected last year by more than 15 percentage points and is popular in the state. He was seen as a top recruit for the Senate last year but declined to run, and he also chose not to run for the Republican presidential nomination himself — saying at the time that he thought he could have more influence as an external voice than as a candidate.

On the 2024 presidential campaign trail, Mr. Sununu stumped with Ms. Haley, Mr. DeSantis and former Gov. Chris Christie, as he weighed which of the three to back. In an interview last month, he said he would talk over his decision with friends and family over the Thanksgiving break. He said he was looking for someone who could beat Mr. Trump and who could connect with voters on “a very retail level.”