In Massachusetts’ Democratic Senate primary, the Associated Press projects incumbent Sen. Ed Markey will win.

Markey, an 80-year-old progressive, staved off a challenge by Rep. Seth Moulton, a 47-year-old Marine Corps veteran from Salem who is a member of the moderate New Democrat Coalition.

The race between Markey and Moulton was defined by the generational divide between the two members of Congress. Moulton argued that it was time for a new generation to represent the state in Washington, especially regarding issues such as artificial intelligence, while Markey, who first went to Washington as a House member in 1976, stood by his track record and said he was more energized than he had ever been.

Sen. Edward Markey speaks after winning the Democratic nomination Sept. 1, 2026, in Boston and Rep. Seth Moulton speaks after losing the Democratic nomination at a primary election night event, Sept. 1, 2026, in Boston.

AP

Markey, who was endorsed by Sens. Bernie Sanders and Elizabeth Warren as well as Rep. Alexandria Ocasio-Cortez, is expected to face Republican John Deaton in November.

This is the second Senate primary in a row in which Markey defeated a younger Democrat. In 2020, Rep. Joe Kennedy III ran against Markey, but lost.

Sen. Edward Markey speaks after winning the Democratic nomination during a primary election night event, Sept. 1, 2026, in Boston.

Charles Krupa/AP Photo

Moulton rose to prominence in 2018 after unsuccessfully attempting to block Nancy Pelosi from regaining her position as speaker of the House. At the time, he also argued that it was time for a new generation of leadership.

“He likes to roll the dice,” Raymond La Raja, a political science professor at the University of Massachusetts Amherst, told ABC News ahead of the primary. “He even ran for president at one point. And here’s another instance of him rolling a dice against an incumbent in this Senate race.”

While Markey and Moulton agreed on many issues, such as abolishing U.S. Immigration and Customs Enforcement (ICE), Moulton placed the generational divide between him and Markey at the center of the Senate primary race.

Rep. Seth Moulton speaks after losing the Democratic nomination at a primary election night event, Sept. 1, 2026, in Boston.

Reba Saldanha/AP Photo

“We need the generation that grew up with the internet and is going to have to live for decades with the consequences of AI to chart the way forward,” Moulton said during a debate in August hosted by ABC affiliate WCVB.

Markey said he had been the leader on internet and artificial intelligence safeguards. In March, he introduced the Youth AI Privacy Act.

“I just want to say it doesn’t make any difference whether it’s called ‘Siri’ or it’s called ‘Claude,'” Markey said during the debate while emphasizing the need for widespread protections.

Sen. Ed Markey speaks during a Get Out the Vote event supporting Markey, Aug. 29, 2026 in Boston.

Mark Stockwell/AP Photo

Moulton responded, “How are we going to effectively regulate and keep big tech accountable if you can’t even tell the difference between big tech programs?”

Rachael Cobb, an associate professor of political science at Suffolk University in Boston, told ABC News ahead of the primary that while Moulton was trying to make his understanding of technology a focus of his campaign, his base remained Democrats who were on the more moderate end of the party.

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“Those kinds of things that happen in debates do not change the outcome of an election generally, especially when the polling is so wide between the two of them,” Cobb said.

Polling released last week by the University of New Hampshire found that 63% of likely Democratic supporters supported Markey, with 28% backing Moulton.

Rep. Seth Moulton, who is challenging Sen. Ed Markey, D-Mass. in the Sept. 1, 2026 primary, speaks to Rich Giannino of Essex, Mass., during a campaign stop at the Agawam Diner, Aug. 29, 2026, in Rowley, Mass.

Josh Reynolds/AP Photo

Incumbent moderate Democrats running in primary races around the U.S. have been facing tough challenges from younger, more progressive candidates for nearly a decade, from Ocasio-Cortez defeating Rep. Joe Crowley in New York in 2018 to Rep. Diana DeGette losing her Colorado primary this past June to democratic socialist Melat Kiros.

In Massachusetts, the Democratic Senate primary was one of several races taking place Tuesday.

In the Democratic primary in Massachusetts’ 8th Congressional District, the Associated Press projected Rep. Stephen Lynch will successfully fend off a challenge from attorney Patrick Roath. 

Lynch, a 71-year-old Democrat who has been in office for nearly 25 years, is generally seen as a moderate. 

In the Democratic primary in Massachusetts’ 6th Congressional District, the Associated Press projects that Dan Koh will win.

Under former President Joe Biden’s administration, Koh served as the deputy director of the White House Office of Intergovernmental Affairs.

Moulton currently represents the district, but Moulton did not seek reelection due to his U.S. Senate primary campaign.

In the 1st Congressional District primary in western Massachusetts, Democratic Rep. Richard Neal, who has been in Congress since 1989, faced off against teacher Jeromie Whalen.

The most prominent Republican race on the ballot Tuesday was the gubernatorial primary.

In the Massachusetts Republican gubernatorial primary, the Associated Press projects that Mike Minogue will win.

Minogue, a former Army infantry officer and medical device company executive, defeated Brian Shortsleeve in the race.

In November, Minogue is expected to take on incumbent Democratic Gov. Maura Healey.