Five Republicans are competing Tuesday in New Hampshire's closely watched primary to challenge incumbent Democrat Sen. Maggie Hassan in November.

The marquee race features retired U.S. Army Brig. Gen. Don Bolduc, a far-right conservative who has echoed former President Trump's claims that the 2020 election was stolen.

Bolduc appears to be in a close contest with state Senate President Chuck Morse, a moderate who is running with the backing of GOP Gov. Chris Sununu.

The three other GOP candidates are Bruce Fenton, Kevin Smith and Vikram Mansharamani.

Hassan is running unopposed.

A University of New Hampshire Survey Center poll conducted late last month showed Bolduc leading Morse 43% to 22%, with the other GOP candidates lingering in the single digits.

Andy Smith, director of UNH's Survey Center, said many New Hampshire voters remain undecided ahead of Tuesday's crowded primary and some have only just started paying attention to the Senate race.

He said Sununu's decision last week to endorse Morse's candidacy could help close the gap with Bolduc, but it remains unclear if it will tip the balance of the race in his favor.

"Bolduc has been winning in the polls but he's been campaigning for the Senate since 2019, so he obviously has higher name recognition than the other candidates," Smith said.

"By and large, all of the candidates all have similar policy positions, so it's really more about their personalities and who can win in November that the partisans seem to be interested in."

Republican groups unsuccessfully tried to get Sununu to challenge Hassan, as part of a strategy to reclaim the Senate in the midterm elections. He instead chose to seek a fourth-term Tuesday as New Hampshire's governor.

Political observers say Sununu's decision could cost Republicans efforts to take over the Senate in November's elections. Republicans and Democrats each hold 50 seats in the Senate ahead of November, with Democratic Vice President Harris serving as a tie-breaking vote.

Hassan is considered among the most vulnerable Senate Democrats seeking reelection this year.

The nonpartisan Cook Political Report has rated the seat as "lean Democrat."

In the money race, Morse has raised more than Bolduc ahead of the primary, according to Federal Election Commission filings. He has raised over $1.5 million, compared to roughly $579,000 to date for Bolduc.

Hassan has raised roughly $24 million this election cycle, according to her FEC filings.

National Republican and Democratic groups have already poured tens of millions of dollars into the general election race, and more spending is expected ahead of the general election.

The Senate Leadership Fund, which is aligned with Senate Minority Leader Mitch McConnell, has reserved $23 million in TV ad spending ahead of the general election.

Besides nominating a GOP candidate to challenge Hassan, New Hampshire voters are also deciding two Republican primaries for House races in Tuesday's primary.

In New Hampshire's 1st Congressional District, four Republican candidates – Gail Huff Brown, Matt Mowers, Russell Prescott, Tim Baxter and Karoline Leavitt – are competing for the party's nomination to challenge incumbent Rep. Chris Pappas.

A University of New Hampshire poll found Mowers, a former State Department official who challenged Pappas in 2020, leading the pack among likely GOP primary voters with 26% of the support among likely voters, compared to 24% for former White House assistant press secretary Leavitt.

In the 2nd District, a crowded ballot of seven candidates are competing to challenge incumbent Democratic Rep. Ann Kuster, who is unopposed.

The UNH poll found Bob Burns, a former deputy state director for Newt Gingrich’s 2012 presidential campaign, leading the pack of contenders, with support from 32% of likely Republican primary voters. He was followed closely by Keene Mayor George Hansel, with 18% of likely voters.

Other GOP candidates in the race are Scott Black, Michael Callis, Jay Mercer, Dean Poirier and Lily Tang.

The nonpartisan Cook Political Report has rated both U.S. House races a "toss up" in the November elections.