(Elise Amedola ~ Associated Press)
The vote came after weeks of mounting legal and political pressure on legislators from both sides in the debate.
With a combination of parliamentary maneuvering, flip-flopping and brinksmanship, lawmakers gave the first round of approval necessary for the amendment to appear on the ballot in 2008. The measure still needs the endorsement of the next legislative session.
If the amendment makes it onto the ballot and residents approve it, it will leave Massachusetts' 8,000 existing gay marriages intact but ban any new ones.
"This is democracy in action. It's not a vengeance campaign. It's not a hate campaign. It's just an opportunity for the people to vote," said Kris Mineau of the Massachusetts Family Institute, a conservative group that opposes gay marriage.
If lawmakers had failed to act on the amendment Tuesday, the measure would have died, and opponents of gay marriage who collected more than 120,000 signatures to try to put the issue on the ballot would have had to start over again.
Democratic Rep. Byron Rushing, who opposed the amendment, said gay marriage supporters had hoped to kill the measure. "We now know who we have to talk to because everyone is on the record," he said.
The pressure on lawmakers came from all sides: Gay rights activists and Democratic Gov.-elect Deval Patrick called on the legislature to let the measure die without a vote. Gay rights opponents -- and Massachusetts' highest court -- demanded an up-or-down vote.
The state Supreme Judicial Court -- the same court that ruled in 2003 that gays have a constitutional right to marry -- declared last week that lawmakers had shirked their constitutional duties by refusing to vote on an amendment submitted by the people. But the justices acknowledged they had no authority to force action.
To advance to the next round, the amendment needed the approval of only 50 of the 200 members of the Legislature. On Tuesday, 61 lawmakers voted in favor, while 132 were opposed.
A few hours later, the lawmakers agreed to reconsider. But then they largely affirmed the original result, with 62 voting in favor of the amendment.
'A huge task'
Arline Isaacson, cochairwoman of the Massachusetts Gay and Lesbian Political Caucus, vowed to continue the fight into the next session to ensure the question is not put on a statewide ballot.
"We have no choice. We're talking about our lives," Isaacson said. But she acknowledged: "It's a huge task. We might not be able to do it."
Earlier in the day, the governor-elect, who supports gay marriage, met with the leaders of the Democratic-controlled legislature to argue against a vote, calling it a "question of conscience."
Patrick charged that the amendment process was being used to "consider reinserting discrimination into the constitution."
"This is not just another question for popular decision. This is a question, under the equal protection clause, about what freedoms the minority is entitled to," Patrick said.
Patrick takes the oath of office Thursday. His predecessor, Gov. Mitt Romney, a Republican who is considering a run for president, opposes gay marriage.
On Tuesday, crowds of gay marriage supporters and opponents returned to the Statehouse to press lawmakers on the issue.
Proponents of the amendment stood at the foot of the Statehouse steps with signs reading "Let the People Vote."
"Legislators are sent to Beacon Hill to vote on a matter, not to not vote on a matter," said one of the sign holders, Paul Ferro, 30.
Opponents of amendment stood on the opposite side of the street, in front of a Civil War memorial, with their own banners. "Let the people marry," read one.
A person on the pro-gay marriage side held a sign that read, "Start Acting Like Christians." An opponent of gay marriage yelled from across the street, "We are Christians, just like you!"
In November, seven states approved gay-marriage bans, joining 20 that had done so in previous elections.
Other states are moving in the opposite direction: New Jersey's gay couples gained new rights last week when the state legalized same-sex civil unions there. Vermont and Connecticut also allow civil unions.
Associated Press writers Glen Johnson and David Weber contributed to this report.