Dan Koh leads the Massachusetts 6th Congressional District Democratic primary field in trader consensus at 71.5 percent, reflecting his substantial fundraising advantage of over $3.5 million and broad endorsements from unions and groups in the open-seat contest to replace Rep. Seth Moulton. Recent internal polls from early May 2026 show a fragmented race with nearly half of likely primary voters undecided, placing state Rep. Tram Nguyen at 13 percent, John Beccia at 10 percent, and Koh tied near that level in initial ballot tests. The September 1 primary timeline favors candidates with established name recognition and resources amid a crowded field of more than a dozen entrants, while lower-priced contenders like Rachel Creemers and others trail without comparable recent momentum or polling visibility.