Former Sen. John Sununu and Rep. Chris Pappas won their party's New Hampshire Senate primaries Tuesday, locking in a competitive general-election fight for the seat retiring Democrat Jeanne Shaheen has held for 18 years.

Sununu topped a crowded Republican field while Pappas beat out four other Democrats, the New York Post reported. The matchup now gives Republicans a genuine shot at flipping a seat in a state Democrats have treated as safe ground, and it hands the GOP a candidate who carries both a famous last name and the full backing of the president.

Democrats need a net gain of four Senate seats in November to reclaim the chamber. Losing Shaheen's seat would be a serious setback for that math, one the party can ill afford as it struggles to hold ground in competitive races across the map.

Sununu returns to familiar turf, with Trump's endorsement in hand

John Sununu first won New Hampshire's Senate seat in 2002, defeating Shaheen when she was governor. She ousted him in a 2008 rematch, and the seat has stayed in Democratic hands ever since. Now Sununu is back, and this time he arrives with something he lacked in his prior campaigns: a presidential endorsement from Donald Trump.

Trump endorsed Sununu in February, posting on Truth Social that Sununu "will work tirelessly to advance our America First Agenda." The endorsement covered the full conservative policy checklist, tax cuts, border security, energy production, school choice, law enforcement, and Second Amendment protections.

"John E. Sununu has my Complete and Total Endorsement, HE WILL NOT LET YOU DOWN."

That backing is notable given the Sununu family's public history with Trump. John Sununu authored a January 2024 op-ed in the New Hampshire Union Leader headlined "Donald Trump is a loser," urging Republicans to support former South Carolina Gov. Nikki Haley in the first-in-the-nation primary. His father, former White House Chief of Staff John H. Sununu, told ABC News in 2016 that Trump had been "a loser all his life." And his brother, former Gov. Chris Sununu, endorsed Haley in 2024 after calling Trump "f, king crazy" at a 2022 Gridiron Club dinner in Washington.

At that same dinner, the younger Sununu added a line that made the rounds in political circles:

"I don't think he's so crazy that you could put him in a mental institution. But I think if he were in one, he ain't getting out."

Trump's decision to endorse John Sununu despite all of that says more about the president's political pragmatism than about any lingering grudge. The Sununu name still carries weight in New Hampshire Republican politics, and winning the seat matters more than settling old scores.

Scott Brown's second New Hampshire bid falls short again

Among the Republicans Sununu defeated was Scott Brown, the former Massachusetts senator who won a 2010 special election to replace the late Ted Kennedy. Brown represented Massachusetts for roughly three years before losing his seat, then moved to New Hampshire and challenged Shaheen in 2014, unsuccessfully. He later served as U.S. Ambassador to New Zealand and Samoa during Trump's first term.

Brown's loss Tuesday marked his second failed attempt to win statewide office in New Hampshire. The result suggests that voters in the Granite State still view him as a transplant rather than a homegrown candidate, especially when measured against a family name as deeply rooted as Sununu.

Shaheen's retirement is part of a broader wave of departures reshaping Congress. Eighty-three members of Congress are heading for the exits after 2026, opening seats in both chambers and creating opportunities for both parties, though Republicans appear better positioned to capitalize in several key races.

Pappas locks down Democratic support, but the margin looks thin

On the Democratic side, Pappas, 46, has served in the House since 2019 and entered the primary as the establishment favorite. He secured endorsements from Shaheen, fellow New Hampshire Sen. Maggie Hassan, and former Vice President Kamala Harris. That heavyweight backing helped him dispatch a field that included Karishma Manzur, a member of the Democratic Socialists of America.

Manzur's candidacy reflected a leftward pull inside the Democratic primary electorate that has shown up in other states as well. In Florida, Democrats recently nominated a democratic socialist for a Senate race that was promptly rated "safely Republican", a pattern that should worry Democratic strategists trying to win swing-state general elections.

Pappas holds a two-point edge over Sununu in the RealClearPolitics polling average for the general election, but more than ten percent of voters remain undecided. A two-point lead with that much uncertainty is barely a lead at all. In a state as volatile as New Hampshire, where ticket-splitting is a tradition, not an anomaly, Sununu has every reason to believe the race is his to win.

The broader Democratic landscape heading into 2028 adds another layer of concern for the party. Progressive figures like Rep. Alexandria Ocasio-Cortez are already eyeing a presidential bid, a prospect that could push the party's national brand further left at exactly the moment it needs to hold moderate voters in states like New Hampshire.

November's stakes go well beyond New Hampshire

For Republicans, flipping Shaheen's seat would be a statement win. Democrats have held both New Hampshire Senate seats for years, and the state's competitive nature has made it a perennial battleground. But the party's four-seat deficit in the Senate means every race matters, and losing a seat they have held for nearly two decades would cut directly into the margin they need.

Sununu brings name recognition, a prior record in the chamber, and a presidential endorsement. Pappas brings incumbency in the House, establishment backing, and a state where Democrats have performed well in recent cycles. The undecided voters, more than one in ten, will decide which advantage matters more.

Polling in New Hampshire has also shown early signs of a broader leftward shift in Democratic primary preferences. AOC's national favorability has been sinking even as she polls competitively in the state's early 2028 presidential primary, a split that captures the tension between what energizes the Democratic base and what wins general elections.

That tension is exactly what Republicans should exploit. If Democrats spend the next two months defending Shaheen's seat instead of going on offense elsewhere, the party's path back to a Senate majority gets narrower with every dollar and every day diverted to New Hampshire.

Sununu and Pappas will spend the fall making their cases. But the fundamentals favor the Republican: an open seat, a president willing to campaign for his candidate, and a Democratic Party that cannot afford to lose yet keeps nominating candidates who make losing easier.