Incumbent Senator Ed Markey holds a clear lead in the Massachusetts Democratic Senate primary due to strong party support and polling advantages over challenger Representative Seth Moulton. At the May 2026 state Democratic convention, Markey secured roughly 73% of delegate votes for the endorsement, while Moulton received 27%—enough to qualify for the September 1 ballot but well short of the majority threshold. Earlier UNH and other surveys showed Markey maintaining double-digit leads among likely Democratic primary voters, bolstered by endorsements from figures like Representative Ayanna Pressley and major labor groups. Moulton's platform emphasizing generational turnover and age limits has not yet shifted the consensus reflected in trader pricing, though the race remains open until votes are cast. Minor candidates trail far behind with limited visibility or organizational backing.