Business is booming.

Mowers Concedes to Leavitt in New Hampshire House G.O.P. Primary

Matt Mowers, 33, a veteran of the State Department and Donald J. Trump’s 2016 presidential campaign, admitted late Tuesday the race for New Hampshire’s first congressional district to Karoline Leavitt, a 25-year-old far-right Republican who served as an aide in the Trump White House news agency.

The Associated Press had not yet announced the race, which had degenerated into a dire battle over who wore the mantle of Trumpism.

“Unfortunately tonight’s results were not our way,” wrote Mr. Mowers in a statement on Twitter at 11:25 pm

In November, Ms. Leavitt will face Representative Chris Pappas, the two-year Democratic congressman who represents the highly competitive district in the eastern and southern parts of the state. Mr Pappas is one of the most vulnerable Democrats this cycle, and his reelection race is seen as a fluke.

If she wins this fall, Ms. Leavitt could be the youngest person ever elected to Congress. The constitution requires House members to be at least 25 years old to serve. Mrs. Leavitt turned 25 last month.

Mr. Mowers entered the race a year ago as the presumed Republican front-runner, benefiting from an infusion of cash from an outside PAC aligned with Representative Kevin McCarthy, the minority leader, who is campaigning to become a speaker.

The candidates have few discernible differences in terms of policy, and the race ended up being less about an ideological divide than about style and tone. It divided the Republican leadership of the House and exposed lingering rifts within the party over Mr Trump’s influence.

Ms. Leavitt, who adopted Mr Trump’s brash style and penchant for inflammatory statements, has been supported by a host of far-right Republicans in Congress, most notably New York Representative Elise Stefanik, the No. 3 Republican, who also has herself styled in the image of the former president. In her campaign, Ms. Leavitt unequivocally reiterated Mr Trump’s lie that the 2020 presidential election was stolen.

Ms. Leavitt leaned against the attacks and the money pouring into the district to beat her, positioning herself as the America First nominee to fight “the swamp” and claiming that if “establishment Republicans” would spend that much to get her to beat, ‘I’m doing something right.” Fox News host Tucker Carlson also elevated her as the anti-establishment candidate in the race.

The Congressional Leadership Fund, a super PAC aligned with Mr. McCarthy, spent more than $1.3 million supporting Mr. mowers. Another super PAC that supports moderate Republicans, Defending Main Street, has spent more than $1.2 million attacking Ms. Leavitt.

The apparent victory for Mrs. Leavitt also marked a victory for Mrs. Stefanik, who harbors ambitions to rise in the party. Her outside group E-Pac, which supports conservative female candidates, has spent the legal maximum, $10,000, to support Ms. Leavitt’s campaign. Ms. Stefanik was also an informal advisor to Ms. Leavitt, who previously served as her communications director.

If Republicans regain control of the House of Representatives and Ms. Leavitt wins her seat in November, she could be a wildcard for Mr. McCarthy in the form of Georgia Representative Marjorie Taylor Greene and other far-right lawmakers who have at times proved a thorn. in the eyes of the minority leader.

But Mrs. Leavitt is running for the general election, bruised by the bitter primaries. Mr Mowers’ campaign ran a website branding her ‘fake MAGA Karoline’. It accused her of “never having a real job outside the swamp,” attending a private school in Massachusetts, and being registered to vote from the “penthouse” apartment where she lived in Washington before returning to New Hampshire to to apply for office.

And Ms. Leavitt’s brash style may be an easier target for Democrats in general elections.

“I think she’s better defeated because Democrats can portray her as an inexperienced ideologue,” said David Wasserman, an election expert at the Cook Political Report, an unbiased newsletter that analyzes elections.