John E. Sununu holds a commanding lead in the Republican primary for New Hampshire’s open U.S. Senate seat, reflecting his strong name recognition from prior service as the state’s senator from 2003 to 2009 and his ties to a prominent political family. He announced his candidacy in late 2025 and filed in June 2026 to replace retiring Democratic incumbent Jeanne Shaheen, quickly securing endorsements including from President Trump while emphasizing fiscal discipline and institutional experience. Scott Brown, a former Massachusetts senator, has mounted a challenge but trails substantially in available polling, limited by perceptions of being an out-of-state candidate. Chris Sununu and Dan Innis register minimal support. With the September 8 primary approaching, Sununu’s position could shift only through unexpected late developments such as major scandals, health issues, or a significant surge in turnout favoring Brown among specific voter blocs.