With six weeks to go until New Hampshire’s first-in-the-nation presidential primary, Gov. Chris Sununu took sides in the race for the 2024 Republican nomination.

The popular governor who’s serving his fourth two-year term steering the Granite State endorsed former ambassador to the United Nations and former South Carolina Gov. Nikki Haley in the race for the White House.

“There was a sweet older woman who has come to a lot of events and I saw her coming in here and she said, ‘So are you going to finally endorse Nikki Haley for president?’” Sununu said Tuesday evening at the McIntyre Ski Area in Manchester. “You bet your ass I am. We’re all in for Nikki Haley.”

Sununu introduced Haley as the “next president of the United States.”

“Let’s not miss this opportunity,” Sununu said. “The entire country is watching.”

Haley has enjoyed momentum in the polls in recent months thanks in part to well-received performances in the first three GOP presidential primary debates. She was grateful for Sununu’s support.

“It’s a great night in New Hampshire,” Haley said. “I mean 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 endorsement as we could hope for.”

While the importance of political endorsements is often overstated and overhyped, Sununu’s backing of Haley could potentially sway independent and moderate voters who often play an influential role in New Hampshire, which holds the first primary and second overall contest in the Republican presidential nominating calendar.

The action started early Tuesday morning when Sununu’s political team released a media advisory announcing that the governor would join Haley and make remarks at town hall event held at McIntyre Ski Area in Manchester.

“I look forward to joining Nikki at her town hall this evening – it’s going to be a lot of fun!” Sununu said in a statement.

Sununu has long been a vocal Republican critic of former President Donald Trump, the commanding front-runner 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.

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, who is once again spending most of this time and resources on New Hampshire as he makes his second White House run, returns to the campaign trail in the Granite State with two events on Wednesday. DeSantis, who is spending most of his time in Iowa, is expected back in the New Hampshire on Friday.

Sununu campaigned with all three candidates on the trail in New Hampshire just before Thanksgiving. “Nikki’s done a great job. She’s been really pounding the pavement in terms of going to various parts of the state, talking to folks, letting them ask her questions,” Sununu told reporters after teaming up with Haley in Hooksett, New Hampshire. “Her message seems to resonate.”

Haley this autumn leapfrogged DeSantis for second place in public opinion polls in New Hampshire and her home state, which holds the first southern contest in the GOP nominating calendar. Christie stands in third place in most of the latest surveys in New Hampshire.

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

Haley has long joked to Sununu about landing the governor’s endorsement.

At the New Hampshire GOP’s annual cookout, held in Manchester early in the summer, 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, Haley then 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.

Sununu’s endorsement of Haley comes a month after popular Republican Gov. Kim Reynolds of Iowa endorsed DeSantis. Since then, Reynolds has joined DeSantis at multiple stops on the Hawkeye State campaign trail.

Sununu said 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 said.

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.”

Neil Levesque, the executive director of the New Hampshire Institute of Politics at Saint Anselm College, said normally it’s debatable whether endorsements matter, except for this instance.

“In this case, this is a game-changing endorsement,” Levesque said.

He cited several reasons.

“Sununu is one of the most talented communicators in politics,” Levesque said. “You combine that with his credibility and popularity in a state like New Hampshire and the fact that he’s going to basically go on the road and sell this to New Hampshire voters and make a persuasive argument for Nikki Haley, I think is going to move the needle.”

Longtime New Hampshire-based Republican strategist Jim Merrill, a veteran of numerous presidential campaigns, agreed 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.”

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 that hopes to boost Haley past Trump.

Trump continues to hold a very formidable and 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.

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.