In a victory for supporters of gay marriage, Massachusetts lawmakers on Thursday blocked a measure to let voters decide whether a constitutional amendment should ban same-sex marriage in the only state that allows it.
State legislators killed the ballot proposal after a four-year attempt by conservative groups to override a historic 2003 court decision that legalized gay marriage in Massachusetts.
Kris Mineau, president of the Massachusetts Family Institute, which backed the measure, said opponents of same-sex marriage were "disappointed and shocked" by the defeat.
"We have a situation here where the politicians have spoken but the people have not," Mineau said. "We have a highly energized base in this state of aroused citizens who, time and time again, have tried to vote on this crucial issue of the definition of marriage, and they have been denied."
Proponents of same-sex marriage worried that the measure would have allowed voters to undo the rights of the state's gay couples.
Lee Swislow, executive director of the Gay & Lesbian Advocates & Defenders, or GLAD, said supporters of gay marriage were confident that legal challenges to the state law would be quelled for now because the failure of the ballot initiative indicated "how much people understand the importance of marriage equality."
But "we are not going away," Mineau said. "We have the opportunity for another petition drive."
The proposal needed support from a quarter of the state's legislators -- 50 votes in two consecutive sessions -- to reach the 2008 statewide ballot. In January, it passed the first round with 62 votes. On Thursday, the measure received 45 votes, with 151 opposing it.
Mineau said about nine legislators "turned on us and changed their minds overnight," after previously supporting the measure. He attributed that to intense lobbying efforts by supporters of same-sex marriage.
Massachusetts is the only state where same-sex marriage is legal. Other states have passed laws allowing same-sex civil unions or domestic partnerships. California's domestic-partnership law, for example, guarantees many of the rights of marriage.
Twenty-six states have passed constitutional amendments banning gay marriage.
Advocates of same-sex marriage hope that Massachusetts' decision marks the end of the legal fight that began in 2001, when seven same-sex couples who had been denied marriage licenses sued. The case reached the state Supreme Judicial Court, which ruled in 2003 that banning same-sex marriage was unconstitutional.
Over the last three years, more than 8,500 same-sex couples have lawfully wedded in the state.
Opponents of same-sex marriage collected more than 170,000 signatures to submit the issue for inclusion on the ballot.
When current Republican presidential candidate Mitt Romney was governor of Massachusetts, he made his attack on the legalization of same-sex marriage a trademark. He was a lead plaintiff in a suit arguing that lawmakers were stripping voters of their right to amend the state constitution.
Thursday's vote was a triumph for Democratic Gov. Deval Patrick, who has said he wants Massachusetts to remain a place where same-sex couples can legally marry. Last week he became the state's first governor to march in Boston's gay-pride parade.
Boston College political scientist Alan Wolfe said a leadership change in the Legislature affected the drop in support for the constitutional amendment. But time had the biggest influence, he said.
"People were gradually getting used to the idea of gay marriage in the state," Wolfe said. "To overturn gay marriage was just too radical a step."