BOSTON (AP) – Both sides along the same-sex marriage divide have vowed to continue their fight a day after the Massachusetts state Legislature soundly defeated a proposed constitutional amendment seeking to ban same-sex marriage.

The vote means Massachusetts will remain the only state in the United States to allow same-sex couples to wed – for now.

A year after lawmakers appeared destined to undo a court order that has allowed thousands of same-sex couples to marry since May 17, 2004, the Legislature voted 157-39 against the proposed constitutional amendment.

Lawmakers were required to approve it in two consecutive sessions before the proposal could move to the statewide ballot in 2006 for a final decision by voters. The measure, which would have allowed civil unions similar to those in the U.S. state of Vermont, won passage by a 105-92 last year.

But the political and social landscape had changed dramatically since then.

Gone was the intensity, the seemingly endless debate and, in some quarters, the taste for stripping away the right for gay and lesbian couples to marry.

“Gay marriage has begun, and life has not changed for the citizens of the commonwealth, with the exception of those who can now marry,” said state Sen. Brian Lees, a Republican who had been a co-sponsor of the amendment. “This amendment which was an appropriate measure or compromise a year ago, is no longer, I feel, a compromise today.”

The moment the vote was announced, cheers erupted from the same-sex marriage supporters who watched the proceedings from the House chamber’s public gallery.

“We have a lot of work ahead of us, but today we celebrate,” Democrat Sen. Jarrett Barrios, an openly gay lawmaker, told the cheering crowd.

The proposal also was opposed by critics of same-sex marriage, who want to push for a more restrictive amendment that would ban both marriage and civil unions for same-sex couples. The earliest that initiative could end up on the ballot is 2008.

“We’re excited. We’re pumped. This is great. This is exactly what we wanted,” said Kris Mineau, president of the Massachusetts Family Institute.

The state’s highest court ruled in November 2003 that same-sex couples had a right under the state constitution to marry. Now, more than 6,100 same-sex couples have been wed in Massachusetts, though officials have barred out-of-state couples from getting married here.

Within a year of the first Massachusetts marriages, 11 states pushed through constitutional amendments banning same-sex marriage, joining six others that had done so earlier.

The Connecticut Legislature approved civil unions in April, joining Vermont in creating the designation that creates the same legal rights as marriage without calling it such. Earlier this month, California lawmakers passed a measure legalizing same-sex marriage, though Gov. Arnold Schwarzenegger has promised to veto it.