Former U.S. Senator John E. Sununu won the Republican primary for New Hampshire's open Senate seat on Tuesday night, according to the Associated Press.

Sununu, backed by President Donald Trump, defeated former Massachusetts Senator Scott Brown and other challengers in dominating fashion, achieving roughly 70 percent of the vote. Brown came in a distant second with 25 percent.

Sununu previously served one term in the U.S. Senate from 2003 to 2009 after serving three terms in the House. He lost reelection to that seat to Shaheen in 2008. Brown, who briefly held a Massachusetts Senate seat and later served as Trump's ambassador to New Zealand, also previously lost to Shaheen in a 2014 Senate bid.

The victory positions Sununu to face Democratic Representative Chris Pappas in November for the seat vacated by retiring three-term Democrat Senator Jeanne Shaheen. Republicans view New Hampshire as one of their strongest opportunities to flip a Democratic-held Senate seat and help maintain their majority.

Trump endorsed Sununu in February despite past criticism from the candidate. The presidential endorsement, along with support from Senate Majority Leader John Thune and the National Republican Senatorial Committee, helped Sununu prevail decisively. Sununu also certainly benefited from his family's long-standing prominence in New Hampshire politics, notably including his brother Chris Sununu's service as Governor until just last year.

On the Democratic side of the race, four-term Representative Chris Pappas won his primary against progressive challenger Karishma Manzur. Pappas, like Sununu, won his Tuesday primary with an overwhelming 65 percent of the vote. Manzur came in second with less than 33 percent.

The November general election matchup between Sununu and Pappas is expected to be one of the cycle's most competitive as both parties fight for control of a swing seat in a historically purple battleground state. Cook Political Report rates New Hampshire's 2026 Senate Race as 'Leans D' and prediction markets currently strongly favor Democrats as of Tuesday night. However, recent polling from Emerson College finds that a direct heads-up race between Pappas and Sununu is a statistical tie.

In an environment narrowly favorable to Democrats, Republicans are confident about their odds of potential gains.