Dan Koh lost a congressional primary by 145 votes in 2018. On Tuesday he won one by 13,335.
Koh took the Democratic nomination in the Sixth Congressional District, the only open congressional seat in Massachusetts this cycle, in a six-way race that ended less closely than almost anyone expected.
The result
| Candidate | Votes | Percent |
|---|---|---|
| Dan Koh | 47,326 | 41.03% |
| Tram Nguyen | 33,991 | 29.47% |
| John Beccia | 13,972 | 12.11% |
| Jamie Belsito | 11,146 | 9.66% |
| Mariah Lancaster | 4,615 | 4.00% |
| Bethany Andres-Beck | 4,292 | 3.72% |
| Total | 115,342 |
Margin: 13,335 votes, 11.56 points. All 237 precincts reporting. Results are unofficial; no certified totals have been published for any race on this ballot.
The withdrawal that did not change the outcome
Mariah Lancaster withdrew from the race on August 29, three days before the election, and endorsed Tram Nguyen.
Her name stayed on the ballot, because Massachusetts law does not remove a candidate this late in the cycle, and she drew 4,615 votes. Those votes exceed the gap between third and fourth place. They are nowhere near the 13,335-vote gap between Koh and Nguyen.
This is a recurring feature of late withdrawals. Ballots are printed weeks in advance, mail voting is already underway, and a withdrawal announced in the final week reaches only the voters who happen to see the news. Lancaster’s 4 percent is roughly what a low-profile candidate draws whether or not they are still running.
Endorsements against money
The race split along a familiar line.
Nguyen, a state representative, carried the institutional progressive endorsements: Representatives Ayanna Pressley and Lori Trahan, and the Boston Globe’s editorial page.
Koh and John Beccia dominated paid media. Between them they accounted for the large majority of advertising in the district.
The paid media won by 11.6 points.
Who Dan Koh is
Koh, 41, of Andover, spent his career in staff roles rather than elected ones. He was chief of staff to Marty Walsh at Boston City Hall, followed Walsh to Washington as chief of staff at the United States Department of Labor, and served as a special assistant in the White House.
His one prior run for office was the 2018 Democratic primary in the Third District, which he lost to Lori Trahan by 145 votes after a recount. He moved districts to run this year.
No victory statement from Koh has been published by any named source as of this writing.
The general election
Koh faces Republican Micah Jones of Essex, who was unopposed in his primary, on November 3.
The Sixth District covers the North Shore and Merrimack Valley, including Lynn, Salem, Peabody, Danvers, Andover, Lawrence, Haverhill, Gloucester, and Newburyport. It has sent a Democrat to Congress in every election since 1996.
The seat opened because Seth Moulton, who had held it since 2015, gave it up to challenge Senator Ed Markey. Moulton lost that primary by 29.7 points and will hold no office after January. Before Moulton, the seat belonged to John Tierney of Salem; a Salem politician has held it continuously since 1997, a streak that ends with Koh, who lives in Andover.
Common questions
Who won the MA-6 Democratic primary?
Dan Koh, with 47,326 votes, 41.03 percent. Tram Nguyen finished second with 33,991, a margin of 13,335 votes. Results are unofficial.
Why was the Sixth District seat open?
Seth Moulton, who held it since 2015, ran for the United States Senate against Ed Markey instead of seeking reelection. He lost that primary.
What happened with Mariah Lancaster?
She withdrew on August 29 and endorsed Tram Nguyen, but remained on the ballot and received 4,615 votes. That was far short of the margin between the top two candidates.
Who does Koh face in November?
Republican Micah Jones of Essex, who ran unopposed in his primary. The general election is November 3, 2026.
Has Koh run for Congress before?
Yes. He lost the 2018 Democratic primary in the Third District to Lori Trahan by 145 votes following a recount.
Vote totals from Associated Press tabulation as of the afternoon of September 2, 2026, at 98.95 percent of expected vote counted. All results are unofficial; the Secretary of the Commonwealth had not published certified results as of publication. General information, not legal advice.