Dan Koh leads the MA-06 Democratic primary field with trader consensus at 73 percent, reflecting his early ballot qualification, dominant fundraising totals exceeding $2 million by early 2026, and multiple local endorsements across the district. The open seat, created after incumbent Seth Moulton launched a Senate bid, drew a crowded field of more than ten candidates. Recent campaign polls from March showed no frontrunner and nearly half of likely primary voters undecided, but Koh’s financial edge and prior federal experience have shifted market positioning since then. Other contenders, including Tram Nguyen and John Beccia, trail in implied probabilities amid ongoing fundraising and endorsement competition ahead of the September 1 primary.