Maryland Lt. Governor Anthony G. Brown (D) as he kicked off his campaign in May. (AP Photo/Jose Luis Magana)

Maryland Lt. Gov. Anthony G. Brown (D) picked up an endorsement of his gubernatorial campaign Friday from the Professional Fire Fighters of Maryland, the latest labor union to offer its support.

“Anthony Brown has always been a partner to Maryland’s professional firefighters, working consistently to ensure we have the support needed to do our jobs,” the organization’s president, Michael Rund, said in a statement in which the union said it represents more than 10,000 active and retired members.

The nod was the latest in a series of endorsements that have come Brown’s way from fellow politicians and interest groups in what is expected to be a highly competitive race next year to succeed Gov. Martin O’Malley (D). Three other labor groups have endorsed Brown thus far.

Brown faces Attorney General Douglas F. Gansler and Del. Heather R. Mizeur (Montgomery) in the June Democratic primary.

Gansler has been largely dismissive of Brown’s endorsements, saying that voters, not “the Democratic establishment,” will determine the outcome of the race.

“As governor, I’m committed to continuing our work to ensure that Maryland’s firefighters have the tools, training, resources and support they need to get the job done,” Brown said in a statement Friday.

The Professional Fire Fighters of Maryland was formed in 1969 as the state association for local chapters of the International Association of Fire Fighters union. It represents 21 locals in the state.