Warren Tolman, one of the two Democrats running for attorney general, on Tuesday will highlight the official backing of Boston Mayor Marty Walsh, who helped Tolman to a narrow edge over rival Maura Healey at the Democratic Party convention in June.

Walsh, a former labor leader and state representative who was elected as mayor in 2013, will join Tolman at a park outside Flames Restaurant on Blue Hill Avenue for a formal endorsement.

Walsh is staying out of in other statewide races, but backed Tolman at the Worcester convention and asked his delegates to do the same. Warren Tolman, a former state senator from Watertown, is the brother of Steve Tolman, the head of the Massachusetts AFL-CIO. At the convention, Tolman received 2,254 delegate votes to Healey’s 2,094 votes.

Jordan Deasy, a top Walsh supporter, blasted out an email out to members of Team Walsh on Tuesday, ahead of the campaign event, saying, “This will be a very tight race in Boston, and we are relying on our team to help deliver Boston for Tolman.”

Healey is a former prosecutor who lives in Charlestown. The winner of the Sept. 9 Democratic primary will face off against John Miller, a Republican attorney from Winchester. The campaign event with Walsh and Tolman is scheduled for 4:15 p.m.