Incumbent Sen. Ed Markey holds a commanding position in the September 1 Democratic primary, backed by strong name recognition, fundraising, and consistent polling leads over challenger Rep. Seth Moulton. Recent debates in July and early August allowed both candidates to contrast records on affordability, infrastructure, and federal policy, yet polls such as the June University of New Hampshire survey show Markey ahead by roughly six points with significant undecided voters remaining. Moulton has emphasized generational turnover and age limits while securing endorsements including from New Jersey Gov.-elect Mikie Sherrill, though these have not closed the gap in trader assessments. Ayanna Pressley and Alexander Rikleen register negligible support, with the latter having withdrawn and endorsed Markey. The market's implied probabilities reflect Markey's structural advantages as the sitting senator in a state where Democratic primaries favor established officeholders.