A constitutional amendment that would ban same-sex marriage in Minnesota took a decisive step Wednesday toward ending up on the 2012 ballot.

After more than three hours of often-emotional debate, the Senate approved the proposed amendment by a vote of 38 to 27. The House, which has not yet taken up the bill, is expected to pass it, as well.

Although Gov. Mark Dayton opposes the measure, which defines marriage as solely between a man and a woman, he has no voice in the decision because constitutional amendments do not require a governor's signature to be placed on the ballot and he can't veto it.

State law already defines marriage as the amendment does, but supporters say the amendment is needed to prevent judges, or a future legislature, from overturning the law.

Although DFL majorities have blocked the amendment for years, now that Republicans control both chambers of the Legislature, passage of it seems nearly assured. Opponents dominated the debate, raising objections that ranged across topics that included religion, discrimination and the economic fallout from adopting the amendment.

Dozens of activists on both sides of the debate filled the Senate gallery and opponents of the amendment conceded that they had little hope of preventing its passage.

"I'm not hopeful at this point," said St. Paul resident Paul Fleege, who hung a banner outside the Senate chamber that declared, "To Be Lesbian or Gay is a Gift from God." "After last November, I knew right away it was going to pass."

"Yes, it's going to pass, but we had to show up and show our opposition," said Monica Meyer, executive director of OutFront Minnesota, the state's largest advocacy group for gays and lesbians."This isn't going to help a single family in Minnesota, but will discriminate against a lot of them."

The bill's sponsor, Sen. Warren Limmer, R-Maple Grove, said the amendment is needed to prevent "a small group of politicians or judges to define marriage" and cited a recent poll sponsored by the Minnesota Family Council that showed that three fourths of the state's residents want the opportunity to vote on the issue. "When I think about it, why shouldn't they?"

Several recent national polls have found that opposition to same-sex marriage has been shrinking to a point where Americans are split on the issue.

"This new majority is very, very wrong," said Sen. Terri Bonoff, DFL-Minnetonka. "This new majority is out of step with the people of Minnesota and the people of this country. People have moved on."

DFLers argued that there's no indication the state's courts are poised to overturn the current state law.

Sen. Scott Dibble, DFL-Minneapolis, who is openly gay, showed a picture of himself and his partner, Richard and emotionally asked, "what is so different about us? What is so dangerous? We work really, really hard to support each other every day."

If the amendment is on the ballot, Dibble predicted "an ugly, angry divisive campaign" will unfold in Minnesota, with millions of dollars being spent by both sides. "This amendment is going to create a climate of hostility and fear."

Here's the amendment: Marriage Vote Senate