Sen. Branden Petersen, a likely co-sponsor of a gay marriage bill to be introduced soon at the Capitol, is the first Republican lawmaker to signal support for allowing same-sex couples to wed.

A Republican state senator who supports legalizing gay marriage in Minnesota said Wednesday that he hopes to convince GOP colleagues to join him in abandoning the party's traditional stand on the issue.

Sen. Branden Petersen, a likely co-sponsor of a gay marriage bill to be introduced soon at the Capitol, is the first Republican lawmaker to signal support for allowing same-sex couples to wed.

Petersen said his backing hinges on a few conditions being met, chief among them that religious exemptions that don't want to perform same-sex marriages would be exempt from doing so. That provision has been a common feature of gay marriage legislation in other states.

"I think the time has come," Petersen told The Associated Press, arguing that it's the conservative position to let gays join an institution that's one of society's fundamental building blocks. He said he hoped his support would sway not just his fellow Republicans wavering on the issue, but Minnesotans in general that it's OK to support gay marriage. The Star Tribune first reported Petersen's break from his party on the issue.

Nailing down Republican support is significant for gay marriage activists preparing for what's likely to be a divisive debate later this spring at the Capitol. While Democrats control the House and Senate, some of the party's rural members hail from socially conservative areas where a majority of voters last fall backed the failed constitutional gay marriage ban.

Voters in Petersen's district, in suburbs north of Minneapolis, supported the marriage ban by a narrow majority. In 2011, as a House member, Petersen voted to put the constitutional ban on the ballot; he declined Wednesday to elaborate on that vote, but acknowledged that having a gay father-in-law has influenced his thinking.

"It's an issue where we all travel on our own path," Petersen said. He acknowledged the possibility of political consequences for his decision, but said that was trumped by doing what he believes is the right thing. He also said working on the bill would put him in a position to win compromises from Democratic sponsors on its provisions.

On Wednesday, Republican activist Andy Parrish blasted Petersen in an email fundraising pitch for his political committee, A Stronger Minnesota. The group "holds 'Republicans' like Petersen accountable for straying from traditional Minnesota values," wrote Parrish, who helped run last fall's unsuccessful campaign to pass the gay marriage ban.

Sen. Dan Hall, a social conservative from Burnsville, said he was disappointed in Petersen but doubted any other Republican senators would join him.

"I think same-sex marriage is wrong," Hall said. "It's a lifestyle that is not healthy spiritually or physically. I think any time the government OKs something, it's an endorsement or promotion of it so I think it's unhealthy for us to do that."

Still, even before Peterson revealed his intentions, the push for a 2013 legislative vote to allow gay marriage had been gaining steam. Gov. Mark Dayton restated his support in his State of the State speech, and Democratic legislative leaders — while not fully embracing the effort — have signaled they won't stand in its way. House Speaker Paul Thissen and Senate Majority Leader Tom Bakk have said they'd vote yes.

Dayton called Petersen's decision "terrific."

"I admire him for his courage and conviction, and hope others will follow to make it bipartisan legislation," Dayton said.

At 27, Petersen is considerably younger than the average Republican senator — personifying a growing generational split in the Republican Party on the issue. Minnesotans United, the group now pushing gay marriage at the Capitol, had recruited a number of young Republican activists and supporters during its successful effort in 2012 to defeat the constitutional gay marriage ban. On Thursday, the group's director Richard Carlbom sent out a fundraising plea touting Petersen's decision.

House and Senate bills to legalize gay marriage are expected in the next few days, though the debate may not get going until later this spring. The chief sponsors are expected to be two Minneapolis Democrats, Sen. Scott Dibble and Rep. Karen Clark, who are both gay and in long-term relationships.