Oct. 31 (Bloomberg) -- San Francisco Mayor Gavin Newsom, who climbed to national prominence as a supporter of same-sex marriage, quit the race to become California’s governor, citing family and mayoral duties.

“With a young family and responsibilities at City Hall, I have found it impossible to commit the time required to complete this effort the way it needs to -- and should be -- done,” Newsom, 42, said yesterday in an e-mailed statement.

Newsom was elected mayor in 2003 after serving two terms as a city supervisor. He announced he would run in the 2010 election on his Facebook page in April. Newsom trailed state Attorney General Jerry Brown, 71, in an Oct. 8 Field Poll. Brown was backed by 47 percent of Democratic voters, compared with 27 percent for Newsom. Brown has yet to declare his candidacy.

Newsom was unable to develop statewide appeal, said Jack Citrin, director of the Institute of Governmental Studies at the University of California, Berkeley.

“I’m surprised that Newsom would withdraw from the race before Jerry Brown has formally entered,” Citrin said in an interview yesterday. “But it was widely known that he was failing badly in the polls and having trouble raising money.”

Brown, who served as governor from 1975 to 1983, had a 31-point lead in Southern California, compared with a 5-point lead in Northern California, according to the poll, administered by San Francisco-based Field Research Corp.

Newsom’s only advantage was among younger voters age 18 to 39, where he led Brown by 8 points, according to the poll. Brown led among voters 40 or older.

Newsom lagged behind in campaign fundraising. The mayor had accumulated $1.2 million as of June 30, compared with Brown’s $7.3 million, the San Francisco Chronicle reported Oct. 6.

‘Failing Badly’

“This is not an easy decision,” Newsom said in the statement. “But it is one made with the best intentions for my wife, my daughter, the residents of the city and county of San Francisco, and California Democrats.”

The winner of next year’s election will replace Arnold Schwarzenegger, who has served two terms, the state limit for sequential terms. Also running are two Republicans: Meg Whitman, former chief executive officer of EBay Inc., and Steve Poizner, the state insurance commissioner.

Newsom won his first term as mayor with a plan to fix the city’s homeless problem by reducing cash payments to welfare recipients and handing out vouchers for housing and services.

The decision to issue marriage licenses for gay couples in 2004 gave Newsom a national presence and unleashed a throng of weddings at City Hall that became news worldwide.

He founded a wine-shop business in San Francisco’s Pacific Heights neighborhood in 1992 that has since grown to include two wineries, a hotel management company, restaurants and retail shops in the Bay Area.

Name Recognition

Newsom’s wife, Jennifer Siebel Newsom, gave birth to their first child last month.

The mayor’s use of Facebook and Twitter to communicate to the public didn’t translate into political success, Citrin said.

“Brown has a huge advantage, which is name recognition, not only his own but his father and sister,” Citrin said, referring to former Governor Edmund Brown Sr. and Kathleen Brown, who served as secretary of state.

To contact the reporters on this story: Dan Levy in San Francisco at dlevy13@bloomberg.net.

Last Updated: October 31, 2009 00:01 EDT