Ed Markey was projected to win the Massachusetts Democratic Senate primary about 30 minutes after polls closed, leading Seth Moulton 75.9% to 24.1% with 3% of ballots counted.
The result handed the 80-year-old incumbent a wide victory over Moulton, 47, whose challenge centered on generational change and calls for "new energy" rather than a sharp policy break.
Markey entered the race with progressive credentials built over 50 years in Congress, including Senate support for resolutions to cut U.S. military aid and munitions sales to Israel.
Moulton had tried to blunt that issue by returning AIPAC donations and rejecting new money from the pro-Israel lobby, but analysts said his focus on Markey's age likely became his main weakness.
The outcome reinforces a broader Democratic lesson already emerging from the race: younger contenders need a substantive message, not just an argument for replacing older leaders.