Ed Markey vs Seth Moulton is the headline Democratic Senate contest in Massachusetts on September 1, 2026, as voters decide whether to renominate 80-year-old incumbent Sen. Ed Markey or choose 47-year-old U.S. Rep. Seth Moulton. Polls are open from 7 a.m. to 8 p.m. Eastern Time, and as of election morning, no winner has been declared.
The race has become one of the most closely watched Democratic primaries of the 2026 election cycle. It combines a debate over age and political experience with disagreements over ideology, technology, foreign policy, health care, transgender rights and the future direction of the Democratic Party.
Markey is seeking his third full Senate term. Moulton, a Marine Corps veteran who has represented Massachusetts’ 6th Congressional District since 2015, is asking Democratic voters to replace a longtime incumbent with a younger generation of leadership.
Latest Update on the Massachusetts Senate Primary
Massachusetts voters are casting ballots Tuesday in a contest that has changed significantly since Moulton entered the race. Early polling showed a competitive contest, but Markey built a substantial advantage during the final weeks.
The latest publicly available polling has consistently put Markey ahead.
A University of Massachusetts Amherst/WCVB poll conducted August 5-12 showed Markey leading Moulton 60% to 32% among likely Democratic primary voters. Seven percent were undecided, while 2% said they would not vote.
An Emerson College survey conducted August 28-29 also showed Markey with a commanding advantage. The poll found the incumbent ahead by a wide margin and reported that younger voters were not breaking toward Moulton despite his campaign’s emphasis on generational change.
The polling represents a major change from earlier in the campaign. A University of New Hampshire poll conducted in June showed Markey leading only 41% to 35%, with 23% undecided.
By the final stretch, Markey had consolidated much of the Democratic base that initially appeared open to Moulton.
Who Is Ed Markey?
Ed Markey has represented Massachusetts in Congress for more than five decades. He served in the U.S. House for 37 years before moving to the Senate in 2013 following John Kerry’s appointment as secretary of state.
Markey won Senate reelection in 2014 and 2020. His 2020 Democratic primary victory over then-Rep. Joe Kennedy III established him as a major figure within the party’s progressive wing.
His 2026 campaign has focused heavily on his legislative record and progressive credentials. Markey has emphasized climate policy, health care, workers’ rights, artificial intelligence regulation and LGBTQ+ rights.
He is particularly associated with the Green New Deal, which he introduced with Rep. Alexandria Ocasio-Cortez, and he has continued advocating for Medicare for All.
Markey’s supporters argue that his age should not overshadow his record. His campaign has repeatedly presented the contest as a choice between the candidates’ ideas and accomplishments rather than their birth dates.
That message has resonated with many Democratic voters. The UMass poll found that more than four in five likely Democratic primary voters approved of Markey’s performance representing Massachusetts in Washington.
Who Is Seth Moulton?
Seth Moulton entered Congress in 2015 after defeating longtime Democratic Rep. John Tierney in the Massachusetts 6th Congressional District primary and general election.
A former Marine Corps officer, Moulton served four tours in Iraq before entering politics. He later earned graduate degrees from Harvard and built a reputation as a national-security-focused Democrat.
Moulton has generally occupied a more moderate position within the Democratic Party than Markey. He is a member of the New Democrat Coalition and has attempted to broaden his appeal beyond the progressive voters who form the core of Markey’s Massachusetts support.
His Senate campaign has centered on generational change.
Moulton argues that Democrats need a new generation of leaders who can address current challenges with a different approach. He has repeatedly highlighted Markey’s age and unusually long tenure in Congress.
That argument has been central to Moulton’s campaign, but it has also created a difficult political challenge. Massachusetts has a strongly Democratic electorate, and Markey’s voting record remains highly progressive.
Age Becomes the Central Issue
The biggest distinction between the candidates is their age.
Markey is 80. Moulton is 47. The difference has made the primary an unusually direct debate about generational leadership.
Moulton has argued that age limits should apply to members of Congress and has questioned whether Markey can provide the type of leadership needed for another six-year Senate term.
Markey has rejected the argument that age should determine the election.
During the first debate in July, Markey responded to Moulton’s criticism by emphasizing the importance of ideas rather than a candidate’s age. The two candidates returned to the issue during subsequent debates.
The age argument also became connected to technology.
Artificial intelligence became a notable campaign issue after Moulton criticized Markey’s ability to keep pace with technological changes. Markey has defended his record on technology policy, including his work on AI regulation and civil rights.
The final debate on August 20 again highlighted differences over age and technology.
The Progressive vs. Moderate Divide
Although Markey and Moulton disagree on important issues, their differences are not always a simple liberal-versus-conservative matchup.
Markey is clearly identified with the progressive wing of the Democratic Party. Moulton has a more moderate record but has emphasized several progressive positions during his Senate campaign.
That dynamic has produced an unusual primary.
Moulton’s strongest argument is that Massachusetts Democrats should choose a younger senator. Markey’s strongest argument is that voters should judge him by his record and progressive priorities.
The contrast became especially clear as prominent progressive leaders rallied around Markey.
Sen. Bernie Sanders endorsed Markey in June. Sen. Elizabeth Warren and Rep. Ayanna Pressley also backed the incumbent. Rep. Alexandria Ocasio-Cortez endorsed Markey on August 20, adding another major progressive voice to his campaign.
The Massachusetts Democratic establishment has also largely favored Markey. Reuters reported that most members of the state’s congressional delegation backed the incumbent, while Moulton did not receive endorsements from members of that delegation.
Moulton’s Support and the Boston Globe Endorsement
Moulton has not been without influential support.
The Boston Globe’s editorial board endorsed him, presenting the congressman as a candidate capable of bringing new leadership and a different approach to Washington. Reuters also reported support for Moulton from New Jersey Gov. Mikie Sherrill and VoteVets.
That backing reflects Moulton’s broader argument that Democratic voters should consider leadership, effectiveness and generational change alongside ideology.
His campaign has also tried to make the contest about more than Markey’s age. Moulton has criticized the senator’s engagement with voters and questioned whether his decades in Washington have produced enough results for Massachusetts.
Markey’s campaign has pushed back aggressively, highlighting Moulton’s voting record and policy positions.
The Transgender Athlete Debate
Transgender rights became one of the more contentious issues in the primary.
Moulton faced criticism for comments he made after the 2024 election concerning transgender athletes competing in girls’ and women’s sports. He later apologized for those remarks.
The issue became a major vulnerability for Moulton among progressive Democrats. Markey repeatedly criticized his opponent over the comments and presented himself as a stronger defender of transgender rights.
The subject appeared in polling as well.
The UMass Amherst/WCVB survey identified Moulton’s past comments on transgender issues as one factor that may have damaged his standing with the state’s Democratic electorate.
For Moulton, the controversy made it more difficult to position himself as a broadly acceptable alternative to Markey in a state where Democratic primary voters tend to be strongly liberal on social issues.
Campaign Debates Sharpen the Differences
Markey and Moulton participated in multiple debates during the primary campaign.
Their first major debate took place July 8 in Chicopee. The candidates clashed over age, health care, financial disclosures and transgender athletes.
A second debate in August revived several of those disputes and introduced another contentious exchange involving allegations about Markey’s name appearing in documents connected to Jeffrey Epstein.
Markey denied ever meeting Epstein and condemned the line of questioning. The exchange became one of the campaign’s most heated moments.
The candidates met for a third and final debate on August 20.
That final confrontation again centered on age, technology and the candidates’ records in office. Moulton continued to argue that Congress needs age limits and new leadership, while Markey defended his ability to continue serving effectively.
Why Markey Has Pulled Ahead
Several factors appear to have helped Markey establish his late-campaign advantage.
First, his support among progressive voters remained strong. Second, he received endorsements from many of the state’s most recognizable Democratic politicians. Third, voters appear to have placed significant value on his experience and existing record.
The UMass poll offered especially strong evidence of that advantage. Markey led Moulton among women, liberals, younger voters, college graduates and several other major demographic groups. Among voters ages 18 to 29, Markey led 53% to 22%.
That result directly challenged Moulton’s assumption that younger voters would naturally favor a younger candidate.
Emerson’s final survey produced a similar finding. Voters under 40 favored Markey by a substantial margin, even though Moulton had made generational change the central theme of his campaign.
What Happens After the Primary?
The winner of the Democratic primary will advance to the November 3 general election.
Republican John Deaton is positioned to face the Democratic nominee in November. The Massachusetts Senate race therefore remains important beyond the Democratic contest, although the state has a strong Democratic voting history.
For Moulton, defeating Markey would represent a major political breakthrough. It would also demonstrate that Massachusetts Democratic voters were willing to reject an established progressive incumbent in favor of a younger candidate with a more moderate profile.
For Markey, victory would allow him to pursue a third full Senate term and extend a congressional career that began more than five decades ago.
What Voters Are Deciding Today
The Massachusetts primary is ultimately about more than two individual candidates.
Voters are deciding whether experience remains an asset when an incumbent is 80 years old. They are also deciding whether generational change is enough to overcome differences in ideology, endorsements and political records.
Moulton has spent much of the campaign asking voters to look toward the future.
Markey has asked them to look at what he has already accomplished and the progressive agenda he says he can continue advancing.
As of September 1, the available evidence strongly favors Markey. Multiple recent polls show him ahead by double digits, and there is no verified indication of a late polling reversal. Still, the primary remains an election rather than a poll, and the official result will not be known until votes are counted after polls close.
For readers searching for the latest Ed Markey vs Seth Moulton developments, the key fact this morning is simple: Massachusetts Democrats are voting today, and the result will determine which candidate carries the Democratic banner into the November Senate race.
The final verdict will come from Massachusetts voters tonight, so stay tuned for the verified primary results and the next chapter of this closely watched Senate contest.