Dan Koh's 74.5% implied probability as frontrunner in the MA-06 Democratic primary reflects his fundraising edge, with over $1.6 million raised compared to incumbent Seth Moulton's $900,000, and a mid-July poll showing Koh leading 35-28% among likely voters. Recent trader sentiment shifted after Koh secured endorsements from the Massachusetts Teachers Association and progressive groups, capitalizing on voter frustration with Moulton's centrist positions on Israel aid and defense spending. Challengers Mariah Lancaster (10.5%) and Kevin Larivee (9.2%) draw support from left-leaning blocs but trail in resources and visibility, while Moulton (9.6%) faces uphill primary dynamics typical for incumbents under challenge. The September 3 primary remains the key date, with no debates pending to alter trajectories.