Stefany Shaheen maintains the strongest position in the New Hampshire First Congressional District Democratic primary, with trader consensus reflecting her consistent polling lead and recent endorsements from all Democratic mayors in the district plus the first major union backing. Her background as a former Portsmouth city councilor and daughter of retiring U.S. Senator Jeanne Shaheen provides notable name recognition and organizational support ahead of the September 8, 2026, primary. Heath Howard and Maura Sullivan trail as state representative and party vice chair respectively, with Sullivan drawing on prior federal experience, while Carleigh Beriont holds lower support as a local selectwoman. Recent polls show Shaheen ahead but with substantial undecided voters, underscoring how late endorsements and campaign momentum could still influence final primary outcomes.