The state Supreme Court's decision to uphold California's constitutional ban on gay marriage - and another impassioned initiative fight as early as next year - present complications for the politician most associated with the cause, San Francisco Mayor Gavin Newsom.

Newsom's political career has been linked to the hot-button issue ever since he directed clerks at San Francisco City Hall to issue marriage licenses to same-sex couples in 2004.

As he embarks on his campaign for governor, the Democrat has been trying to broaden his appeal and define himself as something more than the gay marriage mayor. At the same time, gay rights activists are considering going to the ballot next year in an attempt to overturn the ban, and the intensity of the ensuing campaign could make it difficult for Newsom to connect with the centrist voters he'll need to win a statewide election.

"It certainly underlines Gavin Newsom's previous advocacy for same-sex marriage. I think that might be a two-edged sword for him," said Mark DiCamillo, director of the San Francisco-based Field Poll.

Newsom's leadership on gay marriage should help him in the Democratic primary, when he may face attorney general and former governor Jerry Brown. If he survives the primary, his strong association with the issue could affect the dynamics of the general election, where he would be up against a Republican also seeking centrist voters amid another impassioned initiative campaign.

Despite their liberal image, California voters have told pollsters repeatedly that they are divided over gay marriage. Even as they handed Democrat Barack Obama a 24-point win last November over GOP nominee John McCain, they voted 52 percent in favor of Proposition 8, which enshrined the ban on gay marriage in the state Constitution.

"If (Newsom) were to be the nominee, it would dominate the mainstream, the thinking of most voters, especially those outside the party who may not hold as sympathetic a perception of gay marriage," DiCamillo said.

Two groups, Equality California and the Courage Campaign, are beginning to coalesce behind a 2010 initiative rather than waiting until 2012. They are targeting the same demographics Newsom will have to win, starting with voters in the Central Valley, one of California's most conservative regions.

The area was largely ignored during the failed 2008 campaign against Proposition 8 and is among the regions where Newsom has the least support. Nearly 69 percent of Fresno County voters supported Proposition 8.

Newsom already has been touring the valley and stopping in other moderate to conservative areas, such as San Diego, in a bid to expand his appeal outside the San Francisco Bay area.

During an April town hall-style event in Fresno, Newsom joked about newspaper editorials that questioned his bid for governor.

"They all said, 'Good luck when you go to Fresno.' The issue of marriage equality ... you can't win. The state rejects it," said Newsom, who continues to openly support gay marriage, even before more conservative audiences. "I didn't do it because I waited for a public opinion poll to decide what my values were. I said I'm open to argument, always, but I believe in equality."

The other potential Democratic gubernatorial candidates also support gay marriage. As attorney general, Brown argued to the Supreme Court that Proposition 8 should be overturned. Los Angeles Mayor Antonio Villaraigosa, who has not telegraphed his intentions for next year, is a longtime supporter of gay marriage.

"All three (Democratic candidates) are already 'out,' shall we say, for marriage equality," said Rick Jacobs, president of the Courage Campaign, a nonpartisan issues-based group that does not endorse candidates. "I would argue that they and we are better off with this on the ballot in 2010 because it's going to be an issue anyway."

Some supporters argue that Newsom can turn a 2010 ballot initiative seeking to repeal Proposition 8 to his advantage.

Geoffrey Kors, executive director of Equality California, said if the 41-year-old Newsom is the Democratic nominee, he would draw younger, progressive voters who support overturning Proposition 8.

"Every one of the Democrats running for governor is a supporter of full equality, but clearly Gavin has done a great deal for the cause, at great political risk," Kors said.

The group has not endorsed a candidate.

Democratic strategist Chris Lehane said every politician wants to be known as a courageous leader, but few ever get the opportunity to lead on an issue of major importance and then follow through.