New Hampshire voters head to polls for key U.S. Senate primary

New Hampshire voters head to the polls Tuesday to nominate candidates for a key U.S. Senate race to replace the retiring Democratic Sen. Jeanne Shaheen. Both Democrats and Republicans are aiming to win the seat in their quest to control the Senate in the next Congress.

Rep. Chris Pappas, who leads the fundraising race and has represented the state's 1st Congressional District since 2019, is the favorite to secure the Democratic nomination. He faces a challenge from scientist and democratic socialist Karishma Manzur, who has closed in slightly on Pappas in recent public polls.

On the Republican side, former New Hampshire Sen. John Sununu is the favorite to secure the nomination over former Massachusetts Sen. Scott Brown. Shaheen defeated both Sununu and Brown in different years, but Sununu — whose brother Chris Sununu was a highly popular governor of the Granite State until 2025 — is seen as a formidable candidate in what is shaping up to be a tough election cycle for Republicans as the Iran war drags on and President Donald Trump's popularity slumps.

The New Hampshire Senate race is critical to both parties ahead of November's midterm election. Democratic hopes of flipping the Senate would dim if the party can't hold on to Shaheen's seat, as it needs to net four additional seats to flip the upper chamber. If Republicans flip the seat, it would provide a cushion for the GOP to hold on to its Senate majority by requiring Democrats to flip an additional seat.

The midterms will determine who controls Congress — and subpoena power — during the last two years of Trump's term. If Democrats flip one or both chambers, they are widely expected to launch sweeping investigations of the Trump administration that are likely to rope in companies that have done business with the administration.

Pappas, who has been endorsed by Shaheen and other top Democrats like Sen. Elizabeth Warren, D-Mass., has made anti-corruption efforts a top issue in his campaign. Pappas has largely legislated as a moderate and is a member of the bipartisan Problem Solvers Caucus.

Manzur is running on a platform similar to other democratic socialist candidates who have surged in Democratic primaries across the country, calling for universal healthcare and opposing aid to Israel. She is a scientist by trade, with a Ph.D. in biochemistry and molecular biology.

Pappas has held a lead in the race, but a recent poll from the University of New Hampshire found Manzur had narrowed his lead and was 13 percentage points behind the frontrunner.

Sununu, meanwhile, has campaigned as a moderate Republican willing to work across the aisle. Trump has endorsed Sununu in the race, saying "he will work tirelessly to advance our America First Agenda." But Sununu himself has kept Trump at arm's length in advertising, with the president's approval underwater in the Granite State.

Brown, meanwhile, has targeted "D.C. special interests" in advertising, casting himself as an independent. He has trailed heavily behind Sununu in public polling. Since leaving the Senate, Brown was the U.S. ambassador to New Zealand and Samoa during Trump's first term.