LOWELL -- Massachusetts Democratic Party leaders last night backed a resolution advocating unambiguous support for gay civil marriage, ignoring deep divisions in the party's ranks.

The resolution, approved in a nonbinding vote that left the party's official platform untouched, would appear to be only the second by a state party in the nation. It was approved by a majority voice vote by the approximately 200 members of the state committee present, less than two weeks before the Legislature is scheduled to decide on a proposed constitutional amendment to ban same-sex marriage.

State Party Chairman Philip Johnston said the vote sends a clear message to the nation that "we support protecting the rights of these individuals, and I think most of the rest of the state will support us."

"I think it's very important the party speak out on this issue," he said.

In an interview immediately after the vote, Tom Barbera, a state committee member from Waltham, said: "Massachusetts is on record for supporting full civil rights. To have the party behind this issue is a blessing to me and every lesbian, bisexual, and transgender. It's a historic day." In September, the state committee of the New York Democratic Party passed a similar resolution. It was believed to be the first time a state party nationally had taken such a position.

On Nov. 18, the Massachusetts Supreme Judicial Court issued its landmark ruling that same-sex couples are entitled to enter into civil marriages under the state's constitution. Yesterday, gay rights advocates praised the party for moving so swiftly on the issue, saying it would send an important message to lawmakers as they consider the constitutional amendment.

Members of the state committee unanimously passed another resolution last night, opposing the constitutional amendment and any other attempt to amend the constitution to discriminate against lesbian or gay families.

"It's very significant that they are saying that Democrats don't discriminate," said Arline Isaacson, cochairwoman of the Massachusetts Gay and Lesbian Political Caucus. "Democrats shouldn't discriminate. That doesn't mean that all Democrats have to personally like gay marriage, but they should not discriminate.

"It's a helpful message to legislators, reminding them what the Democratic Party stands for," she said. The Bay State Democratic Party has held an official position in favor of Vermont-style civil unions and has opposed any constitutional amendment that would define marriage as a heterosexual union.The chief sponsor of that amendment is state Representative Philip Travis, a Rehoboth Democrat, and one of the most vociferous supporters of the legislation is House Speaker Thomas M. Finneran, also a Democrat. In addition, the front-runner in the race for the Democratic presidential nomination is Massachusetts Senator John F. Kerry, who has stopped short of endorsing gay marriage. Instead, Kerry has supported gay civil unions and called for states to determine the issue for themselves, rather than the federal government.

Johnston said yesterday that he doubted that Kerry's campaign would be harmed by the resolution, but said it was too important an issue to let campaign considerations affect it.

"He's running a national campaign, and I think every campaign for president has to make its own decision," Johnston said. "But we feel very strongly that this is a matter of basic civil rights for gay and lesbian citizens, and the party should be supporting it."

A spokesman for Kerry could not be reached for comment on the party vote. Some Democrats said that last night's vote on the resolution would be important to those who cast it, but not necessarily to legislators or even many of the party's registered voters.

In reality, some said, the resolution was symbolic.

"It's more important how people in the district feel," said Senator Michael W. Morrissey, a Quincy Democrat, who said he would vote in favor of the constitutional ban on same-sex marriage, so that voters could decide the issue at the ballot box.

"The question is, what's more democratic than putting a question on the ballot?" he said. "Isn't that democratic? That's what the Democrats should be talking about."

Gay marriage opponents said the vote was not surprising, given the generally liberal profile of the Democratic committee, which is made up of directly elected members and others appointed to represent various constituencies, such as labor, gays and lesbians, and African-Americans.

"It is surprising that the state committee has adopted a position that is not held by the party's major presidential candidates, including Senator Kerry," said a statement issued by Ronald A. Crews, spokesman for the Coalition for Marriage, which opposes the SJC's ruling. "We believe that, again, the Democratic State Committee acted out of step from the voters of Massachusetts."

Statewide polls have generally suggested that a slim majority of Massachusetts voters back same-sex marriage, although the most recent surveys appear to reflect a state that is now almost evenly divided on the issue.

The SJC's ruling is scheduled to go into effect in May, unless gay marriage opponents can persuade the court to overturn or further stay its decision.

The state Senate has asked the court for an advisory opinion on a bill that would define marriage as a heterosexual union, but would create civil unions that would offer same-sex couples all of the rights and benefits available to married couples under Massachusetts law. The state Republican Party has made no move to endorse gay marriage. The GOP platform, last updated in 2002, states the party's support for all citizens to be "equal before the law," but does not explicitly refer to gay or lesbian couples.Dominick Ianno, executive director of the state GOP, said the party stands behind Governor Mitt Romney, who has said he favors bestowing a limited list of rights and benefits to same-sex couples, but disapproves of Vermont-style civil unions and same-sex civil marriage. He also supports the movement to amend the constitution to define marriage as a heterosexual union. "We think the governor's got the right approach to protect the definition of marriage as between a man and a woman," Ianno said. "This issue is so important -- and it's really not partisan -- that we should let the voters decide. This is not a Democrat and a Republican issue."

By Raphael Lewis and James Vaznis, Globe Staff, 1/30/2004