"As a former mayor, I know our mayors are on the front lines of the fight to make California's communities stronger, safer, healthier and more livable," Newsom said. "Todd Gloria is the right leader at the right time to be the next mayor of the great city of San Diego."
Gloria has worked with Newsom in the state government since 2016, when he was first elected to the Assembly and Newsom was lieutenant governor. Prior to serving in Sacramento, Newsom served seven years as the mayor of San Francisco.
Gloria has received a litany of endorsements since entering the race in January, particularly among state and federal officials. In June, former Gov. Jerry Brown endorsed Gloria, who has also received the support of the Assembly's Democratic caucus, Rep. Susan Davis, D-San Diego, and San Diego City Attorney Mara Elliott, among others.
"Having Gov. Newsom's support as we seek to build a new San Diego that works for all of us signifies the change our city needs," Gloria said.
"As mayor, I am prepared to work with the governor and our state leaders to make sure San Diego is a real city of opportunity in which every San Diegan can live and have a future in this town."
The mayoral race also includes San Diego City Councilwoman Barbara Bry and activist Tasha Williamson. A Republican has yet to formally declare a run for the technically nonpartisan position, making it increasingly likely that the next mayor will be a Democrat as the city continues to trend to the left.
Bry and Gloria have received the most high-profile endorsements in the race. Rep. Mike Levin, D-Dana Point, former Assembly candidate Sunday Gover and former district attorney candidate Genevieve Jones-Wright have endorsed Bry since she launched her candidacy in January.
Newsom's endorsement comes on the eve of the first forum between the candidates and Bry's first significant public meeting with Gloria since she took a thinly veiled dig at him in June for voting in favor of state legislation that would force cities to hasten housing development.
A fundraising email from Bry's campaign alleged that Sacramento politicians like Gloria are "coming for our homes.'' Although the email did not mention Gloria by name, it referred to him as "my opponent" and included a screenshot of the YIMBY Democrats of San Diego endorsing him via Twitter.
As of July 31, Gloria has raised $646,000 from more than 2,100 donors, while Bry has garnered $531,591 from about 1,200 donors. Williamson, by contrast, raised less than $1,000.