Dan Koh secured the Democratic nomination for Massachusetts’ 6th Congressional District in the September 1 primary after Seth Moulton vacated the seat to challenge for the U.S. Senate. His commanding position stemmed from a substantial fundraising edge exceeding $4.7 million, heavy advertising outlays, and high-profile endorsements from former President Joe Biden and Vice President Kamala Harris that no other candidate matched. These resources supported a broad campaign emphasizing federal experience and opposition to the current administration in the deep-blue North Shore district. In a multi-candidate field, Koh captured roughly 42 percent of the vote, ahead of state Rep. Tram Nguyen by double digits. Official certification or a successful recount remain the only realistic paths that could alter the outcome before the general election.