New Hampshire Gov. Chris Sununu expected to endorse Nikki Haley for president

NEWFIELDS, N.H. – Republican Gov. Chris Sununu of New Hampshire is expected to endorse former ambassador to the United Nations and former South Carolina Gov. Nikki Haley, multiple GOP sources confirmed to Fox News.

The endorsement of the popular governor of the state that holds the first primary and second overall contest in the Republican presidential nominating calendar is all-but-certain to occur when the two team up Tuesday evening at a Haley campaign event in Manchester, New Hampshire.

Sununu's political team released a media advisory early Tuesday morning announcing that the governor would join Haley and make remarks at a town hall at 6 p.m. ET at the McIntyre Ski Area in Manchester.

And in a statement to Fox News, the governor said "I look forward to joining Nikki at her town hall this evening - it's going to be a lot of fun!"

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Republican Gov. Chris Sununu of New Hampshire (left) introduces 2024 GOP presidential candidate and former ambassador to the United Nations and former South Carolina Gov. Nikki Haley at a town hall in Hooksett, N.H. on Nov. 20, 2023  (Fox News - Paul Steinhauser )

Sununu has long been a vocal critic of former President Donald Trump, the commanding frontrunner for the 2024 GOP nomination as he makes his third straight White House run. 

The governor flirted with his own presidential bid before announcing in early June that he wouldn't seek the White House in 2024. Since then, he's said he would eventually endorse in the Republican nomination race and has teamed up repeatedly with many of the GOP contenders as they've campaigned in New Hampshire. 

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In recent weeks, he's said that he had narrowed his endorsement choice down to three candidates – Haley, former New Jersey Gov. Chris Christie, and Florida Gov. Ron DeSantis.

Christie returns to the campaign trail in New Hampshire with two events on Wednesday, and DeSantis is expected back in the Granite State on Friday.

Republican presidential candidate and former U.S. Ambassador to the United Nations Nikki Haley is introduced by New Hampshire Governor Chris Sununu at a campaign town hall meeting in Merrimack, New Hampshire, U.S., September 6, 2023.   REUTERS/Brian Snyder (REUTERS/Brian Snyder)

Haley, who has enjoyed momentum in the polls in recent months, thanks in part to well-received performances in the first three GOP presidential primary debates, leapfrogged DeSantis for second place in New Hampshire and her home state, which holds the first southern contest. Christie stands in third place in most of the latest surveys in New Hampshire.

Haley also aims to make a fight of it in Iowa – the state whose Jan. 15 caucuses lead off the GOP nominating calendar – where the latest polls suggest she is close to pulling even with DeSantis for a distant second place behind Trump.

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Early this past summer, at the New Hampshire GOP's annual cookout, Haley was introduced by Sununu. After exchanging a hug, Haley kicked off her comments to the crowd by saying, "You’ve got a great governor."

With a joke that elicited plenty of laughter, she said, "Governor, I very much worry about your health. What I’m thinking is, I don’t want you to over-stress. I don’t want you to get out there and do too much. So I think what’s best is, go ahead and endorse me now."

Haley was kidding, but in the ensuing months she's jokingly asked Sununu about an endorsement a handful of times.

Republican Gov. Kim Reynolds of Iowa early last month endorsed DeSantis. Since then, Reynolds has joined DeSantis at multiple stops on the Hawkeye State campaign trail. 

Sununu told Fox News Digital last month that his endorsement would also be much more than just a one-day announcement.

"If I get behind a candidate, I’m going to get behind a candidate," he emphasized.

And he later added that he'd put muscle behind his endorsement, "110%."

"That’s the fun part. Are you kidding? I’m not going to do an endorsement and sit on my hands. When I do an endorsement, it's going to be a six-, seven-, eight-, nine-week push, whatever it is, to really make sure folks know where we are. I tend to not leave anything on the table," he emphasized.

And Sununu, who's won election and re-election to four two-year terms as New Hampshire governor, said he'd help whichever candidate he backed "put together a ground game. I think we know how to do it pretty well here."

But he's also tempered expectations that his endorsement might move the needle in the Granite State, telling Fox News last month that "I’m never a big believer that endorsements matter as much as the press think they do."

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Longtime New Hampshire-based Republican strategist Jim Merrilll, a veteran of numerous presidential campaigns, told Fox News the endorsement was "a big deal."

"There's no endorsement in New Hampshire you'd rather have. And it's clear he's going to use it early and often to support Haley."

"Chris Sununu is the Shohei Otani of New Hampshire politics. He's a remarkably gifted, best-in-class talent. He's our state's most successful and impactful Republican of his generation. So his endorsement of Nikki Haley makes this the best day of her campaign and gives her a heck of a clean up hitter down the stretch," Merrill emphasized.

Sununu's backing of Haley comes a couple of weeks after she landed the endorsement of Americans for Prosperity Action, the political wing of the influential and deep-pocketed fiscally conservative network founded by the billionaire Koch Brothers. AFP Action has pledged to spend tens of millions of dollars and mobilize its formidable grassroots operation to boost Haley and help push the Republican Party past Trump.

Former President Donald Trump leaves the stage at a campaign rally Saturday, Nov. 11, 2023, in Claremont, N.H. (AP Photo/Reba Saldanha) (AP Photo/Reba Saldanha)

Trump continues to hold a very large double-digit lead over Haley, DeSantis and the rest of the remaining field of rivals for the nomination in the latest polls in New Hampshire, Iowa, South Carolina, and in national surveys.

But Sununu said last month that Trump's "got a floor, but he’s also got a ceiling," 

"And when you look at the fact that well over 50% of the Republican core-based voter wants somebody else, the fact that in New Hampshire you can have independents that come out – I believe in record numbers – most of which won’t vote for yesterday’s news in terms of Donald Trump," Sununu said.

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.