Three unions, including the healthcare workers’ SEIU 1199, are backing Fields Corner’s Joel Richards in the seven-way race for the District 3 City Council seat.

The other two unions are social workers’ SEIU 509 (social workers) and property service workers’ 32BJ (property service workers).

All three unions combined represent nearly 110,000 people.

“With the issues of quality healthcare, affordable housing, and equitable public education at the forefront of our community’s concerns, we need a counselor who will center working people,” Tim Foley, executive vice president of 1199SEIU, said in a statement. “We believe that Joel is the candidate who can make a meaningful difference and help create a Boston that works for all.”

Richards, a member of the Boston Teachers Union, teaches at the Blackstone in the South End and is a board member of Dorchester’s Little Saigon. The union is staying out of the preliminary.

“Our district is home to the people who make Boston run, providing some of our most essential services,” Richards said. “That is why it is such an honor to be endorsed by a union fighting for the fair treatment and security of so many of those neighbors. We need a City Council actively working to get investment on this side of town and for those workers that fulfill these roles. I look forward to partnering alongside SEIU members and organizers so that all who put their heart and muscle into this city’s prosperity can benefit from it.”

Other unions have backed John FitzGerald, a top official at the Boston Planning and Development Agency. The Greater Boston Labor Council, IBEW Local 103 and North Atlantic Regional Council of Carpenters are among the unions supporting him, while SEIU 888 (state and municipal workers) is supporting labor lawyer Matt Patton.

The preliminary is set for Sept. 12, when the field will be winnowed to two people who face off in the Nov. 7 final election.