Seth Moulton gave up a safe congressional seat to run against Ed Markey. On Tuesday he finds out whether it was worth it.
The Democratic Senate primary is the only statewide race in Massachusetts this year with real stakes on the Democratic ballot, and it has been fought almost entirely on one question that neither man will state plainly: whether an 80-year-old senator should be running for a term that ends when he is 86.
The candidates
Edward J. Markey, 80, of Malden. In Congress since 1976, first in the House and in the Senate since 2013, when he won the seat John Kerry vacated. He is the co-author of the Green New Deal with Alexandria Ocasio-Cortez and the senator most associated with telecommunications and net neutrality law.
Seth Moulton, 47, of Salem. A Marine officer with four tours in Iraq, elected to the Sixth District in 2014 after unseating a nine-term incumbent in a primary. He ran briefly for president in 2019. He is not on the ballot for reelection to the House, which is why his seat is now an open six-way scramble.
John Deaton of Bolton, who challenged Elizabeth Warren in 2024, is unopposed on the Republican ballot. Independent Joe Tache appears in November only.
What the polling says
Markey is favored, consistently and by double digits.
- Suffolk University and the Boston Globe, released August 18: Markey 52 to 38
- UMass Amherst and WCVB, mid-August: Markey by roughly 26, with about 17 percent undecided
- University of New Hampshire, August: Markey by 35
One caveat that matters. The same UNH poll had Moulton within six points in July. A 29-point swing from one pollster in a single month is not a normal result, and we could not reconcile it. Treat the Suffolk and Globe number as the cleanest single measure, and treat the UNH figure as an outlier until someone explains it.
The argument Moulton is actually making
Moulton’s case is generational, and he has been more direct about it than challengers usually are. His refrain through the final debate on August 20 was “It’s not enough.” Not that Markey is wrong, but that he is insufficient to the moment.
The exchange that defined the race came on artificial intelligence. Asked what AI tools he uses personally, Markey answered: “whatever is inside of my iPhone and my iPad, whatever comes up.”
Moulton built his closing week around that answer. It landed because it fit a pre-existing frame rather than creating one, which is what makes a debate moment durable.
Markey then compounded it. On CNN on August 26 he credited his own legislation for producing a “$17 billion settlement against Meta,” which conflated a social media case with AI regulation. The campaign has also spent more than $546,000 with a digital firm and run paid partnerships with Instagram influencers, which Moulton has used to argue the senator is being packaged as digitally fluent rather than being so.
Moulton’s other closing theme is foreign policy. Gold Star families angry over the Iran conflict have anchored his argument that Markey’s institutional seniority has not translated into influence when it mattered.
Why Markey is winning anyway
Because the left consolidated behind him, and did so early.
Markey holds the state Democratic convention endorsement from May. Elizabeth Warren, Bernie Sanders, and Alexandria Ocasio-Cortez have all endorsed him, and all three campaigned with him at IBEW Local 103 in Boston on August 29, three days before the vote. That is an unusual show of force for an incumbent supposedly in trouble, and it is the same coalition that saved him against Joe Kennedy III in 2020.
Moulton has no comparable bloc. He campaigned with New Jersey Governor Mikie Sherrill, which signals a lane, but not a Massachusetts constituency.
There is also a structural problem with the age argument in a Democratic primary. The voters most receptive to it are the least likely to turn out in a September primary, and the voters who reliably do turn out are the ones who have been electing Markey since the Ford administration.
Both candidates have called for abolishing ICE, which tells you how little separates them on policy and why the race collapsed into a referendum on Markey personally.
What Moulton gave up
This is the part worth watching regardless of Tuesday’s result.
By running for Senate, Moulton vacated the Sixth District. Six Democrats are now competing for it with no clear frontrunner and no public polling, in a field where roughly 17 percent of the vote could win. Dan Koh and John Beccia have raised the most money. Tram Nguyen closed with the strongest endorsements, including the Boston Globe editorial board and Attorney General Andrea Campbell.
If Moulton loses on Tuesday, he leaves Congress entirely in January, having traded a safe seat for a primary he was down double digits in through August.
What happens after Tuesday
The winner faces John Deaton in the November 3 general election. Massachusetts has not elected a Republican to the Senate since Scott Brown’s 2010 special election win, and Deaton lost to Warren by more than 19 points in 2024.
In practical terms, Tuesday decides the seat.
How to vote
Polls are open 7 a.m. to 8 p.m. on Tuesday, September 1. Voter registration closed August 22 and Massachusetts has no same-day registration.
Unenrolled voters, who are the largest bloc in the state, may take the Democratic ballot and vote in this race. Doing so does not change your registration.
If you are still holding a mail ballot, Secretary Galvin is advising voters not to mail it. Hand-deliver it to a drop box or your local election office by 8 p.m. Postmarks do not count in a primary.
Common questions
Who is favored, Markey or Moulton?
Markey. A Suffolk University and Boston Globe poll on August 18 had him leading 52 to 38, and other August polling showed similar or larger margins.
Can independents vote in the Markey and Moulton primary?
Yes. Voters registered as unenrolled may request the Democratic ballot. It does not change their registration.
Is Seth Moulton still in Congress?
Through January. He did not seek reelection to the Sixth District in order to run for Senate, so his seat is an open six-way Democratic primary this year.
How old is Ed Markey?
80. He has served in Congress since 1976 and in the Senate since 2013. A new term would run to 2033.
Who won the Republican Senate primary?
It is uncontested. John Deaton of Bolton, who lost to Elizabeth Warren in 2024, is the only Republican on the ballot.
Polling from Suffolk University and the Boston Globe, UMass Amherst and WCVB, and the University of New Hampshire. Debate and campaign reporting from WBUR, GBH, MassLive, and the Boston Herald. Candidate filings from the Secretary of the Commonwealth. General information, not legal advice.