Two unions — Iron Workers Local 7 and Laborers Local 223 — on Tuesday said they’re swinging support over to John FitzGerald, a Boston Planning and Development Agency official, in the race to succeed outgoing Dorchester Councillor Frank Baker.

Dorchester-based Laborers Local 223 is run by Martin F. Walsh, the cousin of Martin J. Walsh, the former US labor secretary and mayor of Boston.

FitzGerald, who lives in Adams Village, is “committed to fighting for good jobs, needed benefits, and economic opportunity for our members and all of Boston's working class,” Walsh of Local 223 said in a statement.

Vin Coyle, business manager for Iron Workers Local 7, which is based in South Boston, added that he’ll be a “strong voice” on the City Council.

The North Atlantic States Regional Council of Carpenters and IBEW Local 103 endorsed FitzGerald in May.

Baker said in April he would not be running for another two-year term. He was first elected in 2011.

Two candidates — Meetinghouse Hill civic activist Jennifer Johnson and public schoolteacher Joel Richards — were already running for District 3 when Baker stepped away from another campaign.

Richards has received support from the Boston Teachers Union, and last week he was endorsed by a Massachusetts wing of the United Auto Workers (UAW) Region 9A. Evan MacKay, of the Harvard Graduate Students Union, which is part of UAW, said he’d be a “strong ally of organized labor.”

The other candidates in the race include former schoolteacher and State House aide Barry Lawton of Uphams Corner/Savin Hill, state transportation official Pat O’Brien of Adams Village, labor lawyer Matt Patton of Savin Hill, former nonprofit leader Ann M. Walsh of Lower Mills, and housing activist Rosalind Wornum of Ashmont.