Updated

A constitutional amendment that would ban gay marriage (search) but legalize civil unions (search) passed two preliminary votes in the Massachusetts Legislature on Thursday night but still faced at least two more legislative hurdles and maneuvering by opponents.

The measure, which could not go on the ballot until November 2006, was first approved after three hours of debate that again turned the spotlight on Massachusetts, where the nation's first legally sanctioned gay marriages are scheduled to take place in mid-May. It passed in another procedural vote later in the evening.

The votes by wide margins were obscured by the fact that several of the most ardent supporters of gay marriage voted in favor of a ban, triggering speculation that they would withdraw their support on the critical final vote needed before this year's constitutional convention ends.

By helping to approve this version of the amendment, these lawmakers eliminated the possibility of other, less appealing versions coming forward at this time.

"Our goal is to kill the ability of other amendments to pass and then kill all of them," said Arline Isaacson, co-leader of the Massachusetts Gay and Lesbian Political Caucus (search). "It's a very long shot strategy. The odds are stacked against us decidedly but it's the only shot we have."

When Isaacson explained her strategy to hundreds of gay activists gathered outside the House chamber, she was greeted with optimistic cheers.

Opponents of gay marriage spoke out passionately against this version of an amendment, arguing that the merger of a ban on gay marriage and approval of civil unions would ask voters to render a single verdict on two diametrically opposed policies.

"The language of that vote is confusing at best to the electorate and will probably, if put on the ballot in that fashion, be defeated," said Rep. Philip Travis, D-Rehoboth, the sponsor of the original amendment, which would have extended no new rights to gay couples.

Due to the elaborate constitutional amendment process, the amendment must be approved by the Legislature at least two more times this year -- perhaps as soon as Thursday night -- and then again during the 2005-06 legislative session, before it could land on the ballot before voters.

Under a landmark high court decision issued in November and reaffirmed in February, gay marriage will become legal in Massachusetts on May 17 -- two and a half years before any constitutional amendment could go on the ballot for popular approval.

The vote in favor of the ban occurred against a backdrop of renewed protests on Beacon Hill, where the Legislature resumed its constitutional convention after a monthlong hiatus filled with behind-the-scenes negotiations.

Ron Crews, head of the Massachusetts Family Institute (search), which has led the opposition of gay marriage, acknowledged the outcome remained unclear, but was encouraged.

"The silver lining out of this is you saw a desire here to protect marriage," he said.

The first constitutional convention ended after three versions of a ban met narrow defeats during two days of passionate debate, pitting civil rights for gay couples against the desire to preserve the traditional definition of marriage.

While the national landscape has shifted dramatically since lawmakers last convened, with unsanctioned gay marriages occurring across the country and President Bush endorsing a federal amendment, the spotlight remained on Massachusetts -- the first state to legalize gay marriages.

"No Hatred. Just loving biblical truth," read posters held by some of the opponents of gay marriage who gathered on the Statehouse steps.

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, a financial management consultant, said as she choked back tears.

If an amendment wins final approval, House Speaker Thomas Finneran has said he will seek to prevent the issuance of marriage licenses -- and the potential legal confusion it could cause -- until the voters are able to weigh in on the amendment.

Gov. Mitt Romney, who opposes gay marriage, has said he would also seek to avoid the legal confusion, but has committed to following the law as it exists May 17.

The crowds began gathering outside the Statehouse at 6 a.m. and by midday more than 3,000 people had filed through security checkpoints into the building, while 1,000 others rallied outside. Hundreds of gay-marriage supporters resumed their post outside the House chambers, singing patriotic hymns and protest ballads, as they did for hours on the last day of the February debate, forcing lawmakers to walk through their ranks as they went to take successive votes on the amendment.

Many opponents of gay marriage came to the Statehouse wearing baseball hats with crosses on them and shirts bearing biblical phrases, promoting heterosexual marriage. Interspersed among the singers, they prayed silently and sang competing hymns.

"Unfortunately, they believe we don't like them," said Maria Reyes, 51, of Boston, an elementary school teacher who came to support a same-sex marriage ban with the Hispanic Baptist Church in Boston. "That's not the issue here. We need to obey God's will."