Almost 57 percent of Mower County voters said “yes” to a constitutional ban on same-sex marriage last November, but the county’s state representative, Jeanne Poppe, voted to legalize gay marriage Thursday, saying it was an opportunity for Minnesotans to practice greater acceptance.

The Austin DFLer said she supported it because “it’s the right thing to do.”

“We’re not going to change who comes into the world and what their sexual orientation is,” she said.

Minnesota is positioned to become the 12th state to approve gay marriages following a historic 75-59 House vote Thursday afternoon. The pivotal vote could make Minnesota the first in the Midwest to pass such a law out of its Legislature, as Iowa, the other, went through the state Supreme Court in 2009. It would allow same-sex weddings beginning Aug. 1.

At the Legislature, the issue of gay marriage is not about approving of who someone is, Poppe said, because lawmakers have no right to do so.

Leading up to the House vote, Poppe said she had heard from constituents in the district, almost entirely made up of Mower County, who were either themselves gay or were relatives of someone who was.

“They want the opportunity to marry,” Poppe said. “They want to be able to do it in their home state.”

Some of those who contacted Poppe had been married to their partners in a state that already allows same-sex marriage, while others have held off because they want to be able to wed in their home state. Several held civil commitment ceremonies, but wanted to affirm their relationship in a stronger way.

Poppe said gay marriage, if it becomes law, would not limit a straight person’s ability to marry in any way.

“This doesn’t impact their ability to have a traditional marriage,” Poppe said.

The House vote is a startling shift in Minnesota, where just six months earlier voters narrowly turned back an effort to ban gay marriage in the state Constitution.

The Senate plans to consider the bill Monday and leaders expect it to pass there, too. Gov. Mark Dayton has pledged to sign it into law.

“My family knew firsthand that same sex couples pay our taxes, we vote, we serve in the military, we take care of our kids and our elders and we run businesses in Minnesota,” said the bill’s sponsor, Rep. Karen Clark, a Minneapolis Democrat who is gay. “Same-sex couples should be treated fairly under the law, including the freedom to marry the person we love.”

Hundreds of supporters and opponents gathered outside the House chamber up to and during the debate, chanting and waving signs. They sang “We Shall Overcome” and a John Lennon song in the minutes before the vote.

Four of the House’s 61 Republicans voted for the bill, while two of its 73 Democrats voted against it.

Opponents argued the bill would alter a centuries-old conception of marriage and leave those people opposed for religious reasons tarred as bigots.

“We’re not. We’re not,” said Rep. Kelby Woodard, R-Belle Plaine. “These are people with deeply held beliefs, including myself.”

Pro-marriage demonstrators filled the hallways outside the House chambers, some dressed in orange T-shirts and holding signs that read, “I Support The Freedom to Marry.” Behind them, opponents held up bright pink signs that simply read, “Vote No.”

Among the demonstrators was Grace McBride, 27, a nurse from St. Paul. She said she and her partner felt compelled to be there to watch history unfold. She said she hopes to get married “as soon as I can” if the bill becomes law.

“I have thought about my wedding since I was a little girl,” she said.

On the other side of the divide, the Rev. Steve Goold of New Hope Church led followers in a morning prayer before they set out to lobby lawmakers. He told them they had the power to change minds and urged them to be respectful.

“Do not shout and boo. Pray,” Goold said.

Galina Komar, a recent Ukrainian immigrant who lives in Bloomington, brought her 4-year-old daughter and one-year-old son to the Capitol to express her religious concerns.

“I do believe in God, and I believe God already created the perfect way to have a family,” Komar said.

But gay marriage supporters also boasted faith leaders in their ranks.

“I’ve celebrated marriages for same-sex couples, but I’ve never been able to sign a marriage license for any of them,” said the Rev. Jay Carlson, pastor at a Minneapolis Lutheran church. “I look forward to the day when I can.”

Eleven other states allow gay marriages — including Rhode Island and Delaware, which approved laws in the past week. Leaders in Illinois — the only Midwestern state other than Minnesota with a Democratic-led statehouse — say that state is close to having the votes to approve a law, too.

But most other states surrounding Minnesota have constitutional bans against same-sex weddings, so the change might not spread to the nation’s heartland nearly as quickly as it has on the coasts and in New England.

The Minnesota push for gay marriage grew out of last fall’s successful campaign to defeat a constitutional amendment that would have banned it. Minnesota became the first state to turn back such an amendment after more than two dozen states had passed one over more than a decade.

The same election put Democrats in full control of state government for the first time in more than two decades, a perfect scenario for gay marriage supporters to swiftly pursue legalization. They tapped the cross-section of citizens, businesses, churches and others who spoke out against the amendment and staged rallies as part of a lobbying effort to build support.

The bill cleared committees in both chambers in March, and with a succession of national polls showing opposition to gay marriage falling away nationally.

“There are kids being raised by grandparents, single parents, two moms or two dads,” said Rep. Laurie Halverson, a Democrat from the Twin Cities suburbs. “Some of those folks are my friends. And we talk about the same things as parents. We talk about large piles of laundry, and how much it hurts to step on a Lego. That’s what we do, because we’re all families.”

—The Associated Press contributed to this report.