Moulton Readies Primary Challenge Against Markey in Massachusetts

Representative Seth Moulton of Massachusetts is moving closer to a primary challenge against Senator Ed Markey in what would be the most prominent test of the Democratic Party’s appetite for generational change after the 2024 election.

Mr. Moulton has been discussing a Senate run, and hiring and interviewing people to work on his campaign, according to five people with knowledge of his activities not authorized to speak publicly. A potential campaign kickoff is expected in early October, two of the people said. He was recently spotted with a film crew in Massachusetts.

A 46-year-old Marine Corps veteran, Mr. Moulton would be taking on Mr. Markey, who was first elected to Congress in 1976 and is one of the party’s progressive stalwarts. Yet Mr. Markey would be 86 at the end of another Senate term, which would make him one of the oldest members.

Mr. Moulton has long been seen as smart, ambitious and impatient. He won his House seat by ousting a Democratic incumbent in a 2014 primary, and during his decade in Congress has chafed at the party’s liberal orthodoxies and at its deference to elders. He briefly ran for president in 2020 and tried to prevent Representative Nancy Pelosi, Democrat of California, from becoming speaker after the 2018 election.

In a statement, Mr. Moulton said his plans for 2026 were not yet settled: “While I continue to look at the best options to represent Massachusetts moving forward, I have not yet made a decision about running for U.S. Senate.”

Mr. Moulton has already banked nearly $2.2 million for his re-election that he could immediately spend on a Senate primary. And he has already hired Joseph Caiazzo, a Democratic strategist who worked for Mr. Markey’s last primary challenger, former Representative Joseph P. Kennedy III, in 2020. Mr. Caiazzo also worked on the New Hampshire presidential campaign of Senator Bernie Sanders of Vermont.