The California Supreme Court's decision allowing same-sex marriage probably throws the politically volatile issue into November, when a proposed state constitutional amendment banning same-sex marriage could spill into the presidential campaign and contests for Congress and the state Legislature.
The court's Thursday ruling was not necessarily good news for the presidential candidates, on whom it could exert problematic pressure.
Republican John McCain's success depends on melding a fractious coalition of GOP conservatives -- who are among those pressing for a ban on same-sex marriage -- with independents and conservative Democrats who tend to recoil from candidates campaigning on social issues. Although a November ballot measure could encourage higher turnout by conservatives who are not naturally aligned with McCain, it also could alienate moderates and young voters, who polls show are far more accepting of same-sex marriage.
Democrats Barack Obama and Hillary Clinton had sketched out a more centrist path than the court's. The decision could encourage Democratic interest groups to press candidates to extend their support for civil unions to same-sex marriage itself.
All three offered finessed responses Thursday, saying that defining marriage is best left to individual states.
In an apparent effort to assuage supporters, McCain reiterated his belief that states have a right to ban same-sex marriage. Obama and Clinton emphasized support for civil unions and equal rights for same-sex couples.
Not surprisingly, the most definitive political statement Thursday came from someone not on the November ballot: California's Republican Gov. Arnold Schwarzenegger.
"I respect the court's decision and as governor, I will uphold its ruling," Schwarzenegger said. "Also, as I have said in the past, I will not support an amendment to the Constitution that would overturn this state Supreme Court ruling."
A coalition of religious and conservative activists has submitted 1.1 million signatures to qualify a November constitutional amendment to say that "only marriage between a man and a woman is valid or recognized in California."
A random sampling of those signatures is underway, and in late June the secretary of state is expected to announce whether, as expected, the groups collected the 763,790 valid signatures necessary to qualify the measure for the November ballot. If approved by voters, the initiative would overturn the Supreme Court decision, according to Andrew Pugno, a lawyer for groups backing the measure. He predicted it would be "a dominant issue" in November.
It would not be the first time that such a measure was wielded in a presidential election year, and it would not be the only one this year; a similar effort will be on the ballot in Florida, and Arizona may also vote on the issue. In 2004, Republicans sought to maximize turnout of conservative evangelical Christians by running anti-gay initiatives in swing states, including Ohio and Florida.
But that year, voters were almost evenly split between Democrats and Republicans when asked who should lead the country. This year, voters are more predisposed to side with Democrats, meaning that Republicans have to work harder to attract them.
"It's a situation that makes it really hard for a Republican who wants to compete for the middle and at the same time hold onto the base," UC Berkeley political science professor Bruce Cain said. "McCain is going to be asked over and over again, 'Where are you on this issue?' Then it seems he either has to abandon the 'straight talk express' and change his view, or live with the consequence of not giving the Christian right what they want."
Democratic consultants said Thursday that the different mix of issues and voters this year may limit the effect of a same-sex marriage initiative. Voters this year are fixed on the economy and the war in Iraq.
"I think it's an environment where people aren't going to pay attention to a lot of noneconomic issues," said Bill Carrick, a Democratic consultant sitting out the presidential race.
Polling indicates that younger voters -- whom the Republicans, making up little more than a third of the state's registered voters, must court -- are more inclined to support same-sex marriage. Republicans pressing too hard risk the same sort of fallout among younger voters that those pushing immigration measures suffered among Latinos.
"At some point, you can't be on the other side of every issue with an entire generation of voters," Carrick said.
Still, GOP pollster Neil Newhouse predicted that an anti-same-sex marriage initiative would motivate religious conservatives to go to the polls and thus will help all Republicans.
"All our data right now shows Democrats are more energized than Republicans in this election," Newhouse said. "If this issue can energize more Republicans and conservatives to vote, then it's a plus for John McCain. . . . It's less relevant how he responds to the issue than how voters respond to it."
Proposition 22, the initiative overturned Thursday, passed in 2000 with the support of 61% of California voters. But recent polls have found the state's voters are now evenly split on same-sex marriage.
Contributing to this report were Times staff writers Cathleen Decker, Michael Finnegan, Maeve Reston, Lee Romney, Stuart Silverstein.