San Francisco ? The California Supreme Court ordered an immediate halt Thursday to same-sex weddings in San Francisco as Massachusetts lawmakers gave preliminary approval to a constitutional amendment to ban gay marriages in the only state where they have been ruled legal.

Teary-eyed couples were quickly turned away at San Francisco’s City Hall, where 4,161 gay couples have tied the knot in the past 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.

Massachusetts took center stage in the national debate over gay marriage after 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.

Lawmakers seeking to put a gay marriage ban before Massachusetts voters were unsuccessful last month during a joint House-Senate session.

San Francisco Mayor Gavin Newsom waded into the debate 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 supported changing the U.S. Constitution to ban same-sex marriages. Lawmakers in dozens of states have also taken up the issue.

Jeanne Rizzo, left, embraces her partner Pali Cooper, right, and their son Christopher Bradshaw, center, as they learn they are 10 minutes too late to be married in San Francisco. The California Supreme Court on Thursday ordered a halt to gay marriages in San Francisco, delivering a victory to conservatives who have fought to block the ceremonies.

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.

The Alliance Defense Fund, a conservative group, and state Atty. Gen. 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 had 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.