Gov. Arnold Schwarzenegger will veto legislation that would have made California the first state in the country to enact legislation allowing gay marriages, his press secretary announced Wednesday.

Schwarzenegger, who has said in the past that he would accept same-sex marriage if voters and the courts embrace it, is leaving it to others to settle the issue.

His veto of the bill that passed the Assembly only the night before was widely expected. But there were some on both sides of the volatile issue who felt Schwarzenegger, a moderate Republican with a libertarian approach to most social issues, might have pulled a surprise and signed the measure into law.

"In Governor Schwarzenegger's personal life and work in public service, he has considered no undertaking to be more noble than the cause of civil rights," press secretary Margita Thompson said in a statement e-mailed to reporters at 5:23 p.m., less than 24 hours after the bill won final approval in the Assembly.

"He believes that gay couples are entitled to full protection under the law and should not be discriminated against based upon their relationship. He is proud that California provides the most rigorous protections in the nation for domestic partners."

But she noted that voters five years ago overwhelmingly approved Proposition 22, which said marriage can only be between a man and woman.

"The governor believes the matter should be determined not by legislative action - which would be unconstitutional - but by court decision or another vote of the people of our state," Thompson's statement said.

A San Francisco judge earlier this year said Proposition 22 violated the equal-protection clause of the state constitution, and Attorney General Bill Lockyer appealed the ruling to a state appeals court. A decision is expected sometime next year.

Assemblyman Mark Leno, the San Francisco Democrat who worked overtime to get his gay marriage bill through both houses of the Legislature, said he's not giving up until he sees Schwarzenegger's signature on a veto message. Schwarzenegger is expected to veto the bill sometime in the next few days, after it clears legislative processing and is formally sent to him.

"Margita Thompson has said all kinds of things in the past that have proven not to be true," Leno said. "I will continue to make my request to meet with the governor and explain why there are millions of people who are suffering under the inequality of the current law and who need this bill to be signed."

He said a rapid veto of the bill would mean Schwarzenegger is "pandering to a far-right political dogma."

"There is no need to move this quickly and disrespect all the people who are in support of this bill," he said.

Schwarzenegger was under intense pressure from both sides of the issue to act their way on Assembly Bill 849, which passed the Assembly on Tuesday night on a 41-35 vote. It got through the Senate a week earlier, 21-15.

Just as the governor finished touring a Salvation Army warehouse in Sacramento on Wednesday to thank volunteers for sending clothing to victims of Hurricane Katrina, Randy Thomasson, president of the Campaign for Children and Families, showed up outside and told reporters he was demanding a veto.

"The only real option to be the people's governor - the only option for the people's governor - is to use the veto pen," Thomasson said. "We're looking for action. We need a veto."

Later in the day, Thomasson gleefully read the governor's announcement to listeners on a Sacramento Christian radio station, where he was hosting a talk show.

"Woo-hoo," Thomasson exulted on the radio. "I'm happy. I want to publicly thank Arnold Schwarzenegger, and I want to thank God right now."

He then led his listeners in a prayer that began, "God, we thank you that you have moved Arnold Schwarzenegger to depart from his support for the homosexual agenda."

Vik Amar, a constitutional authority at Hastings College of the Law in San Francisco who agrees with what Leno is trying to achieve, said Schwarzenegger is on solid legal ground in vetoing the bill.

For one thing, Proposition 22 added a new section of the state's family law code that can only be changed by voters, not the Legislature.

Leno argued that his bill found a way around that requirement by adding new language to the code, rather than amending the language in Proposition 22. That was possible, Leno said, because Proposition 22 was aimed at making sure same-sex marriages allowed by other states weren't sanctioned in California. His bill dealt only with California marriages.

Amar said Leno's interpretation of Proposition 22 was overly narrow and - if correct - would render the statutory initiative in violation of the federal constitution.

"If I was the governor's legal adviser," Amar said, "I would probably advise him that as much as I wish he could sign the bill there's probably not a decent argument that the bill is valid."

Even with the Schwarzenegger veto, Thomasson's group isn't taking any chances.

His organization is one of two circulating petitions for a constitutional ban on gay marriage they say is needed to ensure the courts or a different governor don't make same-sex marriages legal in California.

The state attorney general has said the proposals, which proponents are seeking to qualify for a statewide ballot in 2006, would also strip domestic partners of rights they've gained in recent years.