PORTLAND, Ore. — A judge today ordered Multnomah County to stop issuing marriage licenses to gay and lesbian couples while recommending that Oregon follow the example of Vermont and agree to civil unions.

The ruling by Multnomah County Circuit Judge Frank Bearden effectively ends gay marriage nationally, because Multnomah County was the only jurisdiction known to allow it until May 17, when the state of Massachusetts is slated to begin approving same-sex marriage license applications following a state Supreme Court ruling there.

But Bearden ordered the state to recognize nearly 3,000 gay-marriage licenses approved since March 3, a move hailed by gay rights supporters, who said those would be the country's first legally recognized gay marriages.

The judge also gave lawmakers 90 days after the start of the next legislative session to fashion a law that "would balance the substantive rights of same-sex domestic partners with those of opposite-sex married couples." If no agreement emerges, Multnomah County can resume issuing licenses to gays and lesbians, the judge ruled.

Legislators could convene in Salem as early as June, for a session that was intended to focus on tax reform. But the future of that session is in doubt, because of legislator disagreements on whether it is necessary.

An immediate appeal was expected by agreement of all parties in a lawsuit that has consolidated all the arguments over same-sex unions in hopes of a quick ruling by the Oregon Supreme Court.

Bearden said in a 16-page written opinion that he believes the Oregon Constitution "would allow either a civil union or (marriage) privileges to same-sex couples."

But Bearden also said it was up to the Legislature or the Oregon Supreme Court to determine whether gay marriage should be allowed in the state. Even if the state Supreme Court rules before the Legislature acts, he added, "public debate and legislative action may be required to carry out the court's mandate."

The American Civil Liberties Union, representing nine gay and lesbian couples, joined Multnomah County in a lawsuit against the state and a group called the Defense of Marriage Coalition to challenge an Oregon marriage law that dates back to territorial days.

Multnomah County began issuing marriage licenses to gays and lesbians on March 3 after a legal review determined it was unconstitutional to ban applications from same-sex couples.

County Chairwoman Diane Linn, who issued the order allowing gay marriage license applications, repeated her belief she had a duty to act after the county's chief attorney and independent counsel both determined any ban on gay marriage was unconstitutional.

"This ruling validates Multnomah County's position of defending equality under the Oregon Constitution," Linn said.

The ACLU has argued that denying marriage licenses to those couples amounts to discrimination.

Dave Fidanque, the ACLU executive director in Oregon, said the ruling was important because it recognized the gay marriages that have already taken place.

"These are the first legally recognized gay marriages in the country," Fidanque said. "In no other same-sex marriages that have taken place has there been a court order saying the state must recognize them. That's what's truly historic about this opinion."

But the Defense of Marriage Coalition has argued the state has a right to define marriage as the union between a man and a woman, as long as other rights are not affected.

Kelly Clark, attorney for the coalition, said the Vermont approach should be followed as Judge Bearden recommended.

"He invites the Legislature to solve the problem at the first opportunity," Clark said. "This is where we should have been six weeks ago."

Kevin Neely, a spokesman for the state Attorney General's office, called Bearden's decision "a big step in what will be a bit longer process."

"Our goal from the beginning was to get a ruling from the Supreme Court, but this initial ruling does provide at least some clarity and a framework for moving to that next step," Neely said. "The real key here is to give the Legislature an opportunity to craft a law that the courts will deem constitutionally sound."

Neely said involved parties will have to discuss whether to expedite the appeal to the state Supreme Court, bypassing the Court of Appeals.

Bonnie Tinker, of the pro-gay marriage group Love Makes a Family, was critical of the judge's order to stop gay marriage in Multnomah County for the time being.

"I am extremely disappointed that this will not continue until there is an Oregon Supreme Court decision, especially when there is so much legal opinion that it is unconstitutional to deny same-sex marriages in Oregon," said Tinker, who married her partner of 27 years in the Quaker Church last Saturday.

Portland AP staffers Joseph B. Frazier and Typh Tucker contributed to this report.