Seth Moulton

WORCESTER — Massachusetts Democrats are poised to settle a debate that’s been roiling the party for months: Its endorsement in a hotly contested primary for U.S. Senate.

Delegates pledged to incumbent U.S. Sen. Ed Markey, D-Mass., and U.S. Rep. Seth Moulton, D-6th District, will cast their ballots as activists meet for the second day of their convention at the DCU Center.

They were both visible in the concourses outside the convention hall on Friday and Saturday, as were campaign staffers who were jockeying for last-minute support.

Moulton, of Salem, is expected to clear the 15% threshold to make the Sept. 1 primary ballot. His exact margin was not immediately clear on Saturday morning, but some Democratic activists said he could log as much as 30% support from the assembled delegates.

While Markey, who has served on Capitol Hill for a half-century. has maintained a steady polling advantage, Moulton has whittled away at that gap.

The Malden pol held a 13-point advantage in a University of New Hampshire poll in April. An Emerson College poll in May showed Moulton within 5 points.

Moulton, 47, who briefly ran for president in 2020, has cast the race as one of generational change, arguing that it’s time for a new group of lawmakers to step up on Capitol Hill.

Markey, who will be 80 by Election Day, has argued that his experience and record of bringing home federal money for Massachusetts have earned him another 6-year term.

Hugh Monahan, a retired union electrician from Hanson, on the South Shore, said he’s backing Markey. He’s not concerned by the age gap.

“I’m 78,” he quipped, adding that Markey “still has a lot on the ball.”

Democratic activists resoundingly endorsed Gov. Maura Healey and Lt. Gov. Kim Driscoll on Friday night.

Healey, who’s seeking a second term, warned that her two would-be Republican challengers, former biotech executive Mike Minogue and Baker administration alum Brian Shortsleeve, would bring Trumpism to the Bay State.

“These two guys have a lot of things in common. They’re both millionaires and self-funders, but here’s the biggest thing. They’re both so out of touch with the needs of ordinary people they thought Donald Trump was the right choice for Massachusetts,” Healey said.