Schwarzenegger said the legislation, given final approval Tuesday by lawmakers, would conflict with the intent of voters when they approved an initiative five years ago. Proposition 22 (search) was placed on the ballot to prevent California from recognizing same-sex marriages performed in other states or countries.
"We cannot have a system where the people vote and the Legislature derails that vote," the governor's press secretary, Margita Thompson, said in a statement. "Out of respect for the will of the people, the governor will veto (the bill)."
Proposition 22 stated that "only marriage between a man and a woman is valid or recognized in California." The bill to be vetoed by Schwarzenegger would have defined marriage as a civil contract between "two persons."
In Massachusetts, recognition of gay marriages came through a court ruling.
Gay rights advocates accused Schwarzenegger of betraying the bipartisan ideals that helped get him elected in the 2003 recall.
"Clearly he's pandering to an extreme right wing, which was not how he got elected," said Geoff Kors, executive director of Equality California, one of the bill's sponsors. "He got elected with record numbers of lesbian and gay voters who had not previously voted for a Republican, and he sold us out."
Kate Kendell, executive director of the National Center for Lesbian Rights, said she was not surprised by word of Schwarzenegger's pending veto.
"Any girlie man could have vetoed this legislation," she said, referring to a term Schwarzenegger used previously to mock Democratic legislators. "A real man demonstrating real leadership as governor of the most populous state in the nation would have chosen a different course of action."
The governor has until Oct. 9 to issue the veto. Despite his promise to do so, Schwarzenegger "believes gay couples are entitled to full protection under the law and should not be discriminated against based upon their relationship," Thompson's statement said. "He is proud that California provides the most rigorous protections in the nation for domestic partners."
The Republican governor had indicated previously that he would veto the bill, saying the debate over same-sex marriage should be decided by voters or the courts.
A state appeals court is considering appeals of a lower court ruling earlier this year that overturned Proposition 22 and a 1978 law that first formally defined marriage as a union between a man and a woman. Meanwhile, opponents of same-sex marriages are planning measures on the ballot next year that would place a ban on gay marriages in the state Constitution.
Schwarzenegger's announcement dampened a celebratory mood among the bill's supporters, who only the night before cheered, hugged and kissed as the state Assembly narrowly sent the bill to the governor's desk.
Democratic Assemblyman Paul Koretz had called bans on gay marriage "the last frontier of bigotry and discrimination."
The bill passed the Legislature through the persistence of its main sponsor, Assemblyman Mark Leno, a San Francisco Democrat and one of six openly gay members in the California Legislature.
Leno's original bill failed in the Assembly by four votes in June, but he then linked it to another bill in the Senate, which voted to approve the measure last week.
The Assembly passed the amended bill Tuesday by a bare majority, with the winning margin provided by four Democrats who did not vote on the measure in June.
The vote made the California Legislature the first legislative body in the country to approve same-sex marriage. As in Massachusetts, civil unions in Vermont were granted through court rulings.
"I'm encouraged that the governor is going to stop the runaway Legislature, and he's going to represent the people," said Karen England of the Capitol Resource Institute, a Sacramento group that lobbied against the bill.
"I think Assembly member Leno wanted to rally everyone on his side and he's done exactly the opposite. He's forced his agenda on the rest of us," she said. "But in California the votes of the people do matter."