New Hampshire Senate President Chuck Morse conceded the Republican U.S. Senate primary to retired Army Gen. Don Bolduc, who is poised to face off against Democratic Sen. Maggie Hassan in November's midterm election.

The Associated Press has not yet called the race, but as of 3:31 a.m. ET, Bolduc led with 37% of the vote over Morse's 36%, with 85% of the vote counted.

Bolduc led a crowded field of candidates and now appears to be advancing to a key general election matchup in a crucial battleground state that is one of a handful across the country likely to determine if the GOP wins back the chamber's majority.

Republicans have heavily targeted Hassan, who they view as very vulnerable due to her lackluster poll numbers.

"It’s been a long night & we’ve come up short," Morse wrote on social media. "I want to thank my supporters for all the blood, sweat & tears they poured into this team effort. I just called and wished all the best to @GenDonBolduc. The focus this fall needs to be on defeating Maggie Hassan."

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Republican Senate candidate Don Bolduc reacts during a primary night election party in New Hampshire

New Hampshire Republican U.S. Senate candidate Don Bolduc smiles during a primary night campaign gathering, Tuesday Sept. 13, 2022, in Hampton, New Hampshire. (AP Photo/Reba Saldanha)

"You sent the biggest signal to the establishment tonight. They are going to work for you," Bolduc, who ran as a MAGA style outsider and populist candidate, said late on Tuesday night, after declaring victory in New Hampshire’s GOP Senate primary.

New Hampshire, Rhode Island and Delaware all held nominating contests on Tuesday, as the 2022 primary season came to a close with just eight weeks to go until the Midterms, when the Democrats hope to hold onto their razor-thin majorities in the Senate and House of Representatives.

Additionally, New Hampshire was host to the final in a series of high-profile and competitive Republican Senate primaries, which throughout the past six months have often pitted conservative candidates supported by mainstream Republicans against far-right contenders often aligned with former President Trump and his legions of MAGA loyalists. 

Bolduc, who served 10 tours of duty in the war in Afghanistan, is running as a populist and outsider as he made his second straight run for the GOP Senate nomination in New Hampshire. His 2020 bid was unsuccessful, in part because Trump endorsed Bolduc's rival. After keeping Trump at arm's length in his first Senate campaign, Bolduc has embraced the former president's unproven claims that the 2020 election was "rigged." Bolduc was part of a group of retired generals who signed a letter questioning the legitimacy of the election due to what they charged was "a tremendous amount of fraud."

The former president remained uncharacteristically neutral in New Hampshire’s Senate primary.

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Don Bolduc at New Hampshire primary night event

Retired Army Gen. Don Bolduc at his primary election night event in New Hampshire (Fox News)

While Bolduc gave New Hampshire conservatives plenty of red meat, there were concerns from some Republicans in the state and nationally that a primary victory by the retired general, who has severely struggled with fundraising, will allow Hassan to win re-election.

Two weeks ago, a newly formed super PAC named the White Mountain PAC, which has loose links to longtime Senate Republican Leader Mitch McConnell's political orbit, dished out roughly $4 million to run TV commercials in New Hampshire blasting Bolduc for his "crazy ideas."

"I have taken the arrows from my fellow Republican candidates, and I’m standing strong," Bolduc told supporters at a town hall on Saturday in Laconia, where he was born and raised. "When God made Bolducs, he made oak trees, not willow trees. We don’t bend with the wind. We stand firm." 

"The reason they're afraid of me is they can't control me…. I scare them," Bolduc said when asked by Fox News about the big bucks outside GOP groups were spending to target him.

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NH Gov. Sununu makes an endorsment in the GOP Senate primary

Republican Gov. Chris Sununu of New Hampshire endorsed state Senate President Chuck Morse, at an event in Concord, New Hampshire, on Sept. 8. (Fox News)

Bolduc has also tangled verbally with GOP Gov. Chris Sununu of New Hampshire, who remains very popular with Granite State Republicans.

Bolduc claimed last year that Sununu was a "communist Chinese sympathizer" and that the Sununu family’s business "supports terrorism." While Bolduc has walked back those attacks on the popular governor, he continues to criticize Sununu’s policies during the coronavirus pandemic as "executive overreach." 

A few weeks ago, Sununu said on a popular statewide talk-radio program that Bolduc’s "not a serious candidate, he’s really not, and if he were the GOP nominee, I have no doubt we would have a much harder time… He’s kind of a conspiracy theorist-type candidate."

However, Sununu has tempered his criticism of Bolduc over the past week.

McConnell and other Senate GOP leaders spent a year trying to recruit Sununu to take on Hassan, but the governor announced last November that he would instead run for re-election. On Thursday, he endorsed Morse, who public opinion polls indicated was in second place behind Bolduc.

National Democrats once again meddled in a high-profile Republican primary, as Morse was targeted on TV by a massive seven-figure ad buy from the Senate Majority PAC, the top super PAC supporting Senate Democrats which is aligned with Senate Majority Leader Sen. Chuck Schumer.

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The GOP Senate primary field also included cryptocurrency entrepreneur Bruce Fenton; businessman, economist and author Vikram Mansharamani; and former Londonderry, New Hampshire, town manager Kevin Smith, a former state representative who also served as board chair of the Pease Development Authority.

Sen. Maggie Hassan votes in New Hampshire's primary

Democratic Sen. Maggie Hassan, after voting on primary day in Newfields, New Hampshire, on Sept. 13, 2022 (Fox News)

Hassan, who was unopposed in the Democratic primary, took aim at the eventual GOP nominee after she voted on Tuesday morning.

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"While I have a record of bipartisan results for the Granite State, my opponents are way out of touch with Granite States and way too extreme for Granite Staters," the senator charged as she took questions from reporters.