Former President Joe Biden's May 4 endorsement of Dan Koh, his former White House aide, has solidified trader consensus around Koh as the prohibitive Democratic nominee for Massachusetts' 6th Congressional District, with odds reflecting his fundraising dominance—over $200,000 raised in January alone, far outpacing rivals—and lead in the only credible poll from late April. The open seat, vacated by Rep. Seth Moulton for his U.S. Senate primary bid against Sen. Ed Markey, has drawn a crowded field including Tram Nguyen and John Beccia, but recent local endorsements like Swampscott Select Board Chair Katie Phelan's bolster Koh's momentum ahead of the September 1 primary. While others trail with minimal support, shifts could arise from upcoming forums or late fundraising reports.