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Republican Gov. Chris Sununu of New Hampshire announced Tuesday morning that he will seek reelection and not run for U.S. Senate next year in a race that could ultimately decide whether the GOP wins back control the chamber in the 2022 midterm elections.

Sununu ended months of speculation of whether he would challenge Democratic Sen. Maggie Hassan, by saying, "I'm going to run for a fourth term" as governor.

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"My responsibility is not to the gridlock and politics of Washington, it’s to the citizens of New Hampshire. And I’d rather push myself 120 miles per hour delivering wins for New Hampshire than to slow down and end up on Capitol Hill debating partisan politics without results," Sununu said at a news conference at the governor's mansion in Concord, New Hampshire's capital city.

"That’s why I’m going to run for a fourth term, and I’d be honored if the people of New Hampshire elect me again as their governor," he emphasized.

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National Republicans view Hassan, a first-term senator and Sununu's predecessor as New Hampshire governor, as very vulnerable heading into next year’s midterms. And they saw Sununu, whose poll numbers are flagging but still remain very high among Republicans and in positive territory among independents, and who's carefully navigated his relationship with former President Donald Trump the past six years, as their key to flipping a crucial blue seat red.

New Hampshire Gov. Chris Sununu announces he will run for reelection and not seek a seat in the U.S. Senate Tuesday, Nov. 9, 2021, in Concord, N.H. (Photo: Paul Steinhauser/Fox News Digital) (Fox News Digital)

The Republicans need a net gain of just one seat to recapture the Senate majority they lost when they were swept in January’s twin Senate runoff elections in Georgia. While they’re defending 20 of the 34 seats up for grabs next year – including five open seats – the GOP sees pick up opportunities to flip a blue seat red in the battleground states of Arizona, Georgia, Nevada and New Hampshire.

The intense lobbying effort by national Republicans this year included phone calls from Senate GOP Leader Sen. Mitch McConnell of Kentucky and other prominent politicians. Sununu was viewed as one of the Senate GOP's top recruitment prospects.

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Sununu's well-received appearance this past weekend at the Republican Jewish Coalition's annual leadership conference in Las Vegas – a major gathering of top party leaders, activists, rainmakers and mega donors – sparked more speculation that Sununu was leaning toward a Senate run, which could have made the New Hampshire showdown one of the most competitive, combative and expensive races in the country.

Sununu addresses RJC

GOP Gov. Chris Sununu of New Hampshire addresses the crowd at the Republican Jewish Coalition's annual leadership meeting in Las Vegas, on Nov. 5, 2021. (Fox News)

"I might run for governor. I might run for Senate. I don’t know," Sununu told the crowd on Friday night before boasting "trust me, I’m going to win either way." 

"Sorry, Maggie," he added. 

Sen. Ted Cruz of Texas, the conservative firebrand from Texas and runner-up to Trump in the 2016 Republican presidential nomination race, told the audience at the Las Vegas conference to urge Sununu to run for the Senate. Cruz addressed the crowd a few minutes after Sununu.

"Every person here needs to come up to Chris and say ‘governor is great but you need to run for Senate.’ Because this man could single handily retire Chuck Schumer as majority leader of the Senate," Cruz said to applause.

Sununu, at his news conference on Tuesday, shared that "there was a period where I was definitely leaning to running (for the Senate) and I definitely went back and forth a bit."

The governor told Fox News that "while this might have been an interesting adventure and maybe, ultimately a better step, not just in terms of political opportunity…but at the end of the day I feel very at peace with this decision. I really do. I think it’s best for the state. I think it’s best for myself."

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"When you look at what their (senators) job is and what a governor’s job is… it’s not even close. I can’ tell you how many senators told me ‘you just going to have to wait around a couple of years to get anything done.’ Can you imagine me sitting around a couple of years," Sununu emphasized. "They debate and talk and nothing gets done…. That’s not the world I live in."

And earlier in his news conference, the governor also blasted the Senate, saying that while sometimes makes "20 tough decisions a day" as governor, "you don't get to do any of that in the Senate. You debate and talk; nothing gets done. And as I said, sometimes that's considered a win, doing nothing. I can't."

Sununu did tout once again that if he had run for Senate, he was confident he would have run.

He also inferred that he didn't give the Senate GOP leadership a heads up on his decision.

Asked by Fox News if he had alerted officials in D.C. in advance of Tuesday morning's announcement, and what their reaction was, Sununu said "I guess you'll have to let them know…I haven't talked to them." 

National Republican Senatorial Committee communications director Chris Hartline charged in a statement, following Sununu's announcement, that "Hassan is the least popular and most vulnerable incumbent in the U.S. Senate."

And he emphasized that the GOP has "lots of great candidates in New Hampshire and we look forward to one of them beating Hassan next November."

The governor won reelection last year in a landslide, and his coattails swept the GOP into the majority in both houses of the state legislature.

Sununu has always stated that he's more of an executive that a lawmaker, and when asked about the possibility of launching a 2024 run for the GOP presidential nomination, the governor said "I haven't ruled out going to Washington, just not as a senator right now."

With Sununu not running for Senate, speculation quickly turned to other Republicans who might launch a campaign.

Former GOP Sen. Scott Brown of Massachusetts, who moved to New Hampshire and came close to defeating Democratic Sen. Jeanne Shaheen in 2014, and who served as ambassador to New Zealand during the Trump administration, told Fox News that he hopes Sununu reconsiders his decision. 

Brown shared that moments after Sununu's announcement, he started getting calls from Republicans in New Hampshire and the nation's capital urging him to run. But Brown said that a 2022 campaign is not on his radar right now, as he's supporting his wife Gail Huff Brown's GOP run for Congress in New Hampshire's First District.

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Speculation also instantly shined on former GOP Sen. Kelly Ayotte, who was defeated by Hassan by just over 1,000 votes in 2016. 

But sources close to Ayotte quickly shot down suggestions that the former senator would run for her old job next year.

And in a statement, she said that she and her husband would "continue to focus on our family, professional careers, and electing Republicans here at home."

GOP sources say there's chatter that New Hampshire Education Department commissioner Frank Edelblut, who was likely to run for governor if Sununu launched a a Senate campaign, may now bid for Senate in the wake of Sununu's announcement.

And Republican sources in the state also told Fox News that longtime New Hampshire Senate President Chuck Morse wasn't ruling out a U.S. Senate bid. Morse had been mulling a run for governor if Sununu had launched a Senate campaign.

There's already one declared Republican candidate in the 2022 race for Senate in New Hampshire. Retired Gen. Don Bolduc, who unsuccessfully ran for the 2020 GOP Senate nomination, launched his campaign nearly a year ago. 

Sununu was the crown jewel of GOP Senate recruits, and his decision not to run is seen as a relief the national Democrats hoping to hold onto their razor thin Senate majority. But the battle for New Hampshire's Senate seat may still be very competitive.

Hassan campaign manager Aaron Jacobs said in a statement "Senator Hassan won her last race by 1,017 votes, and we know that no matter who emerges as the Republican nominee this is going to be a hard-fought race."

The Senator has shown that she can work across the aisle to get results for Granite Staters — and that is why she has a record of winning tough races. Our campaign is ready for the challenge ahead," Jacobs emphasized.