Teary-eyed couples were quickly turned away at San Francisco's City Hall, where 4,161 gay couples have tied the knot in the last month.
"We were filling out the application and they told us to stop," said Art Adams, who was the first to be denied as he and partner Devin Baker sought a license. "It's heartbreaking. I don't understand why two people in love should be prevented from expressing it."
On the other side of the country, Massachusetts legislators returned to the Capitol to consider a constitutional amendment that would strip gay couples of their court-granted right to marriage but allow civil unions.
The amendment won approval during two preliminary votes, but its final passage is far from certain. Gay marriage supporters were conducting procedural maneuvers that could ultimately lead to the proposal's defeat.
The earliest a ban could end up on a statewide ballot is November 2006, more than two years after same-sex couples can start getting married in Massachusetts.
Due to the elaborate constitutional-amendment process, the ban must be approved by the Legislature at least three more times this year and then again during the 2005-06 legislative session. Then it would go before voters in 2006.
While the State Supreme Court has ruled couples could begin to get their marriage licenses in May, late last night the government made a plea to the court to hold off on any same-sex marriages until the legislative debate is resolved, reports CBS News Correspondent Mika Brzezinski.
The proposal was adopted 129-69 with the help of several gay marriage advocates, triggering speculation that they could withdraw their support on the critical final vote needed before the end of this year's constitutional convention.
Massachusetts took center stage in the national debate over gay marriage following a landmark decision by its highest court in November that was reaffirmed last month. The rulings set the stage for the nation's first legally sanctioned gay marriages on May 17.
"Same-sex marriage will be legal in Massachusetts in May and nothing in this amendment will change that. And if this amendment does survive all of its challenges over the next two years and makes it into the constitution there could be, emphasis on could, two classes of married people in the state," said CBSNews.com Legal Analyst Andrew Cohen.
"The language of this amendment obviously is different from the language of the federal constitutional amendment endorsed last month by President Bush. So even if this state amendment passes muster over the next two years it won't count for purposes of the federal amendment. The state would have to go through another process," said Cohen.
Lawmakers seeking to put a gay marriage ban before Massachusetts voters were unsuccessful during a joint House-Senate session last month.
San Francisco Mayor Gavin Newsom waded into the debate at about the same time, ordering his administration on Feb. 12 to issue same-sex marriage licenses.
Newsom's defiance of California law prompted several other cities across the nation to follow suit, and President Bush last month cited the San Francisco weddings when he announced that he supports changing the U.S. Constitution to ban same-sex marriages. Lawmakers in dozens of states have also taken up the issue.
The high court's unanimous decision Thursday marked a victory for conservatives who have been fighting for a month to block the rush to the altar by gay couples.
Had the court declined to intervene, the legal battle over gay marriage in California would have taken years as gay marriage lawsuits traveled through the state's lower courts.
"They restored order to chaos in San Francisco," said Joshua Carden, an attorney with the conservative Alliance Defense Fund.
"I don't think this decision presages a result against proponents of same-sex marriage but I don't think they ought to feel very confident either. It looks like the California court is very reluctant to jump into this dispute now, with both feet, maybe in part because of what the justices there see going on with their colleagues in Massachusetts," said Cohen.
"It will be easier to rescind a few thousand licenses than tens of thousands of them if San Francisco ultimately loses this battle," he said.
The Alliance Defense Fund, a fellow conservative group and state Attorney General Bill Lockyer had asked the court to immediately block the gay marriages.
Jon Davidson, an attorney for the Lambda Legal Defense and Education Fund, a gay rights legal aid group, said the ruling simply puts the issue on hold for now. About 2,688 couples have wedding appointments that are now on hold.
"The court has put everything on pause rather than stop," he said. "They are saying that until we hear this, you are on pause."
The court did not rule on the legality of gay marriages, and justices indicated they would decide in the coming months whether Newsom had the authority to allow the weddings.
In Massachusetts, both sides acknowledged that they face a long battle.
Several of the most ardent supporters of gay marriage actually gave preliminary approval to the ban. By doing that, the lawmakers eliminated the possibility of other, less appealing versions coming forward at this time. They hope to withdraw support on the crucial final vote needed before the end of the session.
The gay marriage ban needs to be approved by two consecutive Legislatures before reaching the ballot. The earliest that could happen is November 2006.
"The silver lining out of this is you saw a desire here to protect marriage," Ron Crews, head of the Massachusetts Family Institute, said of the preliminary approval.
The first constitutional convention ended after three versions of a gay marriage ban met narrow defeats during two days of passionate debate, pitting civil rights against the desire to preserve the traditional definition of marriage.
By 6 a.m. Thursday, hundreds of people stood at the Statehouse entrance before the start of the second convention, and others chanted, waved flags and sang Gospel music on the sidewalks.
"No Hatred. Just loving biblical truth," read posters held by some of the opponents of gay marriage.
Lynn Tibbets, 50, of Boston, held a sign urging "No discrimination in the constitution." "It used to just make me mad the people on the other side. Now it just makes me sad," Tibbets said as she choked back tears.