ST. PAUL — A group of Minnesota Republicans introduced a bill Wednesday to let gay couples join in civil unions, calling it an alternative to gay marriage that could end a corrosive fight on the issue. Gay marriage supporters quickly condemned the measure as inferior and unequal.

“We have a choice right now. We can engage in a gay marriage debate where we’re going to have half of Minnesota fighting half of Minnesota on this issue,” said Rep. Pat Garofalo, R-Farmington. “If you look at the issue of civil unions, the overwhelming majority of Minnesotans support this.”

But Sen. Scott Dibble, chief Senate sponsor of the gay marriage bill, said civil unions are no longer sufficient at a time when nine U.S. states and the District of Columbia have allowed gay marriage. Eight more U.S. states allow some form of civil union or domestic partnership.

“Civil unions are a separate and unequal status,” Dibble said.

The Minneapolis Democrat said one limit of such unions is they would be good only in Minnesota, and not transferrable to other states that allow gay marriage or even their own version of civil unions. It also could leave Minnesota gay couples in civil unions without recognition under federal laws that benefit married couples in the event the U.S. Supreme Court strikes down the federal Defense of Marriage Act.

“We’re moving forward with marriage this year,” Dibble said. “The time is right.”

Rep. Tim Kelly, R-Red Wing, is spearheading the civil union effort. He said they would give gay couples all the benefits of marriage but also keep government out of the debate over whether it should be legal.

The push for gay marriage springboards from Minnesota voters’ defeat last fall of a constitutional amendment that would have banned it.

Kelly was one of only four Republicans in the Legislature who voted against putting that amendment on the ballot. But he said it’s too big a leap from the amendment’s rejection to assuming that Minnesotans are ready for legal gay marriage.

Kelly was joined by Garofalo and Reps. Andrea Kieffer of Woodbury and Denny McNamara of Hastings. The latter three all voted to put the amendment on the ballot.

Kelly said he’s recruited one Democratic co-sponsor for his bill, Rep. Kim Norton of Rochester. He said he hoped to attract more Democrats.

Minnesota’s gay marriage debate is unfolding at a time of rapid change nationally. Last week, the U.S. Supreme Court heard arguments over legal challenges to California’s voter-approved gay marriage ban and the federal Defense of Marriage Act. If the court strikes down the latter, it could mean that gay couples married under state laws would have access to federal benefits afforded to married couples. Rulings are not expected until later this summer.

Meanwhile, a growing number of national politicians are declaring support for gay marriage, including two Republican U.S. senators, Rob Portman of Ohio and Mark Kirk of Illinois.

Both of Minnesota’s Democratic U.S. senators, Amy Klobuchar and Al Franken, support gay marriage.

So far in Minnesota, only one Republican state lawmaker has said he’d vote to legalize gay marriage: Sen. Branden Peterson of Andover. Kelly, Kieffer, Garofalo and McNamara all said they’d vote against it.

Several Republicans represent legislative districts where a majority of voters opposed last fall’s gay marriage amendment, and some of those lawmakers have said they’re still undecided about the bill.

Kelly said if he can’t get a committee hearing on his proposal, he might offer it as an amendment to the gay marriage bill when it comes up on the House floor. That’s expected to happen later this session. But House Speaker Paul Thissen, a Democrat, supports gay marriage. On Wednesday, he called civil unions an idea “whose time has passed.”

The Colorado Legislature voted to legalize civil unions last month starting May 1. As in Minnesota, Democrats hold the Governor’s Office and control the Legislature. But Colorado state Sen. Pat Steadman, who sponsored the bill there, said his state’s ban on gay marriage in its constitution made civil unions the best available option.

“It’s not full equality,” Steadman said. “It’s not the final destination.”

Minnesotans United, the group leading the push for the gay marriage bill, said Kelly’s proposal would leave gay couples as second-class citizens. Autumn Leva, spokeswoman for the chief group opposed to gay marriage, was cool to it, too.

She said her group would examine Kelly’s bill but worried that it left little distinction between civil unions and full marriage rights.

“What the problem with marriage?” Dibble asked. “People fall in love, they want to make a lifetime commitment together, they want to celebrate that commitment in front of friends and families. So why civil unions? Why something different and substandard and inferior? It reminds me of times in the Deep South: You can’t drink from that water fountain. You can’t walk through that door.”