© Reuters/Robert SorboWashington state Governor Christine Gregoire signs legislation legalizing gay marriage in the state, in Olympia, Washington February 13, 2012.
Governor Christine Gregoire signed legislation on Monday to make Washington state the seventh in the United States to legalize gay marriage, but opponents vowed to try to prevent the law from taking effect.

Gregoire, a Democrat and a Roman Catholic, signed the measure to raucous applause during a ceremony in the ornate reception room of the Olympia statehouse, declaring, "This is a very proud moment. ... I'm proud of who and what we are as a state." It was the latest victory for the U.S. gay rights movement.

Six other states already recognize gay marriage - New York, Massachusetts, Connecticut, Vermont, New Hampshire and Iowa - as does the District of Columbia.

The measure, which won approval from state lawmakers on Wednesday, remains essentially on hold until at least early June, following a standard enactment period that runs until 90 days after Washington's legislative session ends.

Opponents of the statute have vowed to seek its repeal through a ballot measure in November that could delay enactment further or halt it entirely. The issue is also likely to figure in the state's Republican presidential politics.

Still, the bill-signing marked another key victory for gay rights advocates after a federal appeals court declared a voter-approved gay marriage ban in California unconstitutional last week, and the New Jersey state Senate approved a same-sex marriage bill earlier on Monday.

Several dozen protesters, including members of the group Knights of Columbus, stood silently in the Capitol Rotunda overlooking the reception hall holding signs with slogans espousing marriages of "one man, one woman."

Republican White House candidate Rick Santorum, a devout Catholic and an outspoken foe of same-sex marriage, was making two stops in Washington state on Monday to galvanize support for the Republican caucuses there on March 3.

He was to meet with Republican lawmakers in Olympia in the afternoon, then give a speech in Tacoma on Monday night.

Anticipating the repeal campaign that lies ahead later this year, the governor added, "I ask all Washingtonians to look into your hearts and ask yourselves - isn't it time? ... We in this state stand proud for equality."

Democrats, who control both legislative bodies in Olympia, accounted for the lion's share of support for the measure. The stage for swift passage was set after Gregoire, who is in her last term of office, said last month she would endorse the law.

Several prominent Washington-based companies employing tens of thousands of workers in the state have supported the bill, including Microsoft, Amazon and Starbucks.

Opponents were led by Roman Catholic bishops and other religious conservatives.

Similar Efforts Elsewhere

Supporters of same-sex marriage are pushing similar statutes in Maryland and New Jersey, whose Democratic-controlled state Senate in Trenton approved a gay marriage bill earlier on Monday. Republican Governor Chris Christie has vowed to veto it if it reaches his desk.

A referendum to legalize gay marriage in Maine has qualified for the November ballot there.

Two of Washington state's leading proponents of gay marriage, state Representative Jamie Pedersen and state Senator Ed Murray, hailed the work of Olympia's legislature.

"Years from now, our kids will look back and wonder what all the fuss was about," said Pedersen, who has four young children with his partner of 10 years. Murray, who has said he will marry his companion of nearly 20 years, added, "My friends, welcome to the other side of the rainbow."

In the meantime, opponents of same-sex matrimony have said they would seek to overturn the legislation via one of two ballot measures -- a referendum for repeal or an initiative defining marriage as the exclusive domain of heterosexual couples.

If a repeal referendum qualifies for the November ballot, the gay marriage law would be suspended until the certification of election returns in December, before it is either repealed or goes into effect.

But qualification of a proposed initiative defining matrimony as restricted to one man and one woman would not, in and of itself, prevent gay marriages from proceeding under the newly passed statute starting on June 7.

It remains unclear whether gay weddings performed in the interim would be nullified if an initiative were to pass in November.