Walsh signals that he backs Zakim over Galvin in primary battle

Mayor Martin J. Walsh spoke during his second inauguration in January. Keith Bedford/Globe Staff/File

WORCESTER — Mayor Martin J. Walsh is throwing his support behind City Councilor Josh Zakim in his challenge to longtime Secretary of State William F. Galvin, delivering what could be a critical boost to the 34-year-old Zakim at Saturday’s state Democratic Convention.

Walsh, who is in Texas for a personal trip, telegraphed his support to Boston-based delegates through supporters in the DCU Center, a source close to the second-term mayor said. The party will vote on an endorsed candidate Saturday afternoon.

Walsh’s decision could be a blow to Galvin, a six-term Brighton Democrat who is facing his first primary opponent in more than a decade.

Galvin, 67, needs to show a strong majority is behind him at the convention as he fends off the younger challenger. Zakim’s campaign reflects a major shift in Massachusetts politics in which a new generation of candidates is threatening longtime Democratic stalwarts.

Zakim has built his campaign on a message of delivering fresh ideas, including support for same-day voter registration, to the low-profile but critical office, which is responsible for overseeing the state’s election system, enforcing securities rules, and monitoring a range of other government functions. He’s also drawn endorsements from younger members of the state Senate, and US Representative Seth Moulton , who was first elected in 2014 after defeating a Democrat incumbent in a primary.

Galvin has emphasized his record since first winning the seat in 1994 and is leaning on his deep ties to the party to help carry him among the Democratic faithful.

Both Zakim and Galvin are expected to clear the 15 percent hurdle needed to make the primary ballot on Sept. 4, but party observers are keenly watching the final tally.

At a convention where approximately one-fifth of the delegates are first-time attendees, some said they’re ready to embrace a new face.

“I think it’s time to shake it up,” said Chuck Collins, a 58-year-old delegate from Jamaica Plain. “I’m looking for people with a particular spark in this moment. And it’s only when Zakim got in the race that Galvin started talking about . . . basic reforms.”

Sam Chery, an East Boston delegate, said he decided Friday night to back Zakim. “It’s his willingness to want change and push change,” the 32-year-old said.

“I think people are split,” he added of Boston delegates. “I think people see Galvin as a stalwart and he’s done a good job. But some people feel things do need to change.”

Others say Galvin’s deep knowledge of the office shouldn’t be discounted.

“He has the experience, and he knows what he’s doing,” said Barry Cooley, a 28-year-old delegate from Roslindale who is backing the incumbent. “Zakim just seems to be running on the fact that he’s a new face.”

Laura Kershner, a delegate from Cambridge, said she is supporting Galvin because she’s been impressed with how he’s operated his office.

“I don’t see why you throw out someone who runs the office well just to have a new person,” she said.

Galvin has at times faced turbulence during his reelection fight. He said he disciplined several employees in his office after an internal review found that they had performed campaign tasks for him while on public time or while taking sick leave.

Zakim has called for an internal investigation into the practice, though he acknowledged that he, too, has benefited from public employees helping his reelection campaign to the council last year. Zakim said the staffers used personal time in each instance.