Chris Pappas

A third Republican candidate, state Senator Daniel E. Innis, dropped out of the running and endorsed Sununu in September.

Polling suggests Sununu may be better positioned than Brown for a general election showdown with Representative Chris Pappas, 45, the Democratic front-runner.

Brown has sought to position himself as an ardently pro-Trump candidate, and there were signs Sununu could face lingering blowback for having criticized Trump during the 2024 election cycle, when he called Trump “a loser‘’ in an opinion piece he wrote.

But the president made clear Sunday that whatever past differences he and Sununu may have had are water under the bridge, at least as far as this race is concerned. In a statement on his social media platform, Trump wrote that he is honored to endorse Sununu, whom he called an “America First Patriot.”

“John is strongly supported by the most Highly Respected Leaders in New Hampshire, and many Republicans in the U.S. Senate and, as your next Senator, he will work tirelessly to advance our America First Agenda,” Trump wrote, lauding Sununu’s stances on the economy, tax cuts, energy policy, health care, school choice, border security, supporting military and law enforcement, and defending Second Amendment rights.

“John E. Sununu has my Complete and Total Endorsement — HE WILL NOT LET YOU DOWN. MAKE AMERICA GREAT AGAIN — ELECT JOHN E. SUNUNU!" he added.

Alex Latcham, executive director of the Senate Leadership Fund, a political action committee affiliated with Senate Majority Leader John Thune, asserted that Trump’s endorsement of Sununu has “put an end to the primary.”

Brown, however, signaled Sunday that he’s not ready to back down. In a statement, he said New Hampshire voters “deserve a choice between candidates.”

“I am running to ensure our America First agenda is led by someone who views this mission not as a career path, but as a continuation of a lifelong commitment to service,” he said.

“My priorities for New Hampshire remain clear: a stronger economy, a secure border, reliable and affordable energy and better health care for our veterans,” he added.

This isn’t Brown’s first time going toe to toe with a fellow former US senator in such a contest. In 2014, he beat former senator Robert C. Smith in New Hampshire’s GOP primary, then lost to Shaheen in the general election.

In a statement, Sununu thanked Trump for the support and said he launched his campaign with a vow to put New Hampshire first and focus on jobs, the economy, and affordability.

“That focus and promise is resonating across the state,” he said, “and we are running neck and neck with Chris Pappas.”

A survey from the University of New Hampshire conducted in January showed Sununu trailing 5 percentage points behind Pappas in a hypothetical matchup, while another 5 percent of likely voters remained undecided about the race.

Pappas campaign manager Rachel Petri said the endorsement from Trump “confirms what people in New Hampshire have known for decades: John Sununu will sell out Granite Staters to advance his political career.”

“Granite Staters want a new generation of leadership,” Petri added, “and that’s Chris Pappas, whose record shows he will work with anyone to help people get ahead and he will take on anyone — including John Sununu, Donald Trump, and their corporate special interest backers — to do what’s best for New Hampshire.”

In the 2024 presidential election, Trump lost New Hampshire by 2.8 percentage points, and his job approval rating remains underwater. So while his endorsement may bolster Sununu in the GOP primary, it might complicate Sununu’s path to victory in the general election, since Democrats in New Hampshire and across the country are framing the midterms as a referendum on Trump and his GOP allies.

Pappas indicated on social media that he welcomes the news of Trump’s endorsement. “I’m Chris Pappas, and I approve this message,” he wrote, resharing a screenshot of Trump’s endorsement.

Kristen Cianci, a spokesperson for the Republican National Committee, said Trump’s endorsement underscores that this race is a priority “and that Republicans are fully prepared to show up in November.”

Sununu’s younger brother, Chris Sununu, and their father, John H. Sununu, each served as governor of New Hampshire. John H. Sununu also went on to serve as White House chief of staff for President George H.W. Bush.

Republicans in Washington, including Trump, nudged the Sununus to try to flip the Senate seat, but Chris Sununu — who wrapped up his eight-year tenure as governor in January 2025 — said in April he wouldn’t enter the Senate race.

John E. Sununu launched his campaign in October, saying he wanted to return to the Senate to help work through Washington’s dysfunction.

“Somebody has to step up and lower the temperature,” he said in a campaign launch video. “Somebody has to get things done.”