The Hawaii Fire Fighters Association union announced Thursday its endorsement of former Honolulu Mayor Mufi Hannemann in the Democratic primary race for Hawaii’s 2nd Congressional District, representing rural Oahu and the neighbor islands.

"Mufi has been a strong supporter of the fire service and the labor community," the union said in a news release.

Hannemann is running to replace U.S. Rep. Mazie Hirono, who is vacating the seat to run for the U.S. Senate. 

He faces City Councilwoman Tulsi Gabbard, former Office of Hawaiian Affairs Chief advocate Esther Kiaaina, Hilo attorney Bob Marx and Honolulu attorney Rafael del Castillo in the Democratic primary. No Republican has declared for the race.

The Hawaii Fire Fighters Association’s statewide membership consists of more than 2,800 active-duty and retired firefighters from all four counties with the majority of members on Oahu.