Frank Baker, who isn’t running for reelection in Dorchester-based District 3, plans to hit the campaign trail this week to support his candidate to replace him on the City Council: John FitzGerald, the Boston Planning and Development Agency official.

Baker is slated to join FitzGerald and Marty Walsh, the former Biden labor chief and mayor, at a July 15 canvass at 33 Romsey Street, and formally announce his endorsement. Walsh, now the head of the NHL players union, told the Reporter on Sunday he is backing FitzGerald, in his first public endorsement since his last days in City Hall and his time in the Biden administration.

Unions are also appearing to coalesce around FitzGerald. Three more unions — AFSCME Council 93, IBEW Local 2222, and the Sprinklerfitters Local 550 — are set to announce their backing, adding to a list that includes Iron Workers Local 7, Laborers Local 223, the North Atlantic States Regional Council of Carpenters and IBEW Local 103.

Baker said he's endorsing FitzGerald due to the candidate’s 17 years working for the city of Boston in various roles. FitzGerald currently works for the BPDA as deputy director of real estate operations.

“I think John has a good temperament,” Baker said Wednesday. “I think his heart is in the right place. The most important thing is he cares for the city.”

FitzGerald, an Adams Village resident, is one of seven candidates running to replace Baker. FitzGerald’s father, the late Mission Hill state Rep. Kevin Fitzgerald, served with Walsh in the state Legislature.

The other candidates in the race are Meetinghouse Hill activist Jennifer Johnson; former government aide and schoolteacher Barry Lawton of Uphams Corner/Savin Hill; Savin Hill labor lawyer Matt Patton; Fields Corner teacher and pastor Joel Richards; former education nonprofit leader Ann M. Walsh of Lower Mills; and housing activist Rosalind Wornum of Ashmont.

District 3 councillors have had a history of endorsing and supporting candidates for their seats. James Byrne backed Maureen Feeney, his City Hall aide, to replace him in 1993. When she opted against another term in 2011, she backed Cedar Grove civic activist John O’Toole over Baker and others in the race.

Baker jumped into the race after Mayor Thomas Menino’s administration shut down the printing department. In January, when he leaves public office, Baker will have spent more than 36 years working for the city.

Baker said this April he would not be running for another two-year term. During his tenure, he drew praise for providing constituent services and was known as a fiscal watchdog, while also drawing criticism for outbursts on the Council floor, from invoking the sectarian conflict in Northern Ireland during the Council’s redistricting process to likening councilors to pigs during the annual city budget process.