John E. Sununu holds a commanding lead in the September 8 Republican primary for New Hampshire's open U.S. Senate seat due to his prior service in that chamber from 2003 to 2009, deep name recognition within the state, and ties to the politically prominent Sununu family. Recent polling shows him ahead of Scott Brown by margins exceeding 30 points, supported by strong fundraising that has exceeded $3.6 million and a campaign emphasis on fiscal discipline and institutional experience. Brown, a former Massachusetts senator, remains the clearest alternative but has not closed the gap amid limited shifts in voter sentiment over the past month. Minor candidates including Chris Sununu and Dan Innis register negligible support. A late surge by Brown or an unexpected endorsement could narrow the contest, though Sununu's structural advantages make such movement unlikely before primary day.