1 of 5
Jim Mone, Associated Press
A gay marriage supporter waves the U.S. flag and a rainbow flag as supporters and opponents of Minnesota's gay marriage bill gather in the State Capitol rotunda in St. Paul as the Senate prepared to take up the issue Monday, May 13, 2013 in St. Paul, Minn. The bill passed the Minnesota House last week.

ST. PAUL, Minn. — Supporters of gay marriage in Minnesota taped blue and orange hearts Monday onto the state Capitol steps, creating a path into the building for lawmakers preparing an afternoon vote on whether to allow same-sex weddings starting in August.

The Senate was scheduled to open debate at noon on a bill that would make Minnesota the 12th state to legalize gay marriage and the first to pass such a measure out of its Legislature. Iowa allows gay weddings due to a court ruling.

The chamber's majority Democratic leaders have said they expect it to pass. The House passed the bill last Thursday by a 75-59 vote. Assuming a repeat in the Senate, the bill would head to Democratic Gov. Mark Dayton, who has promised to sign it as early as Tuesday.

A festive mood took hold among gay marriage supporters at the Capitol. Hundreds of proponents arrived hours before the vote. A choir sang from the steps, adorned with the hearts cut out of construction paper.

Down the hill in downtown St. Paul, Mayor Chris Coleman ordered the Wabasha Street Bridge festooned in rainbow gay pride flags to mark the occasion, and temporarily renamed it the "Freedom to Marry Bridge." He also proclaimed this week as "Freedom to Marry Week" in the capital city.

Sen. Scott Dibble, the gay marriage bill's sponsor, ascended the steps to a roar from the crowd. He told them they should be proud to "serve witness to the dream we all hold in our hearts."

"This is your day," he said. "You made this happen."

Dibble was legally married to his partner, Richard Leyva, in California, and they will mark their fifth anniversary on Aug. 17. They said they plan to have an affirming ceremony in Minnesota that day. The bill takes effect on Aug. 1.

Micah Thaun Tran, of Golden Valley, has been with his partner for 13 years and said they're planning a fall wedding in Grand Marais, a small ceremony with friends and family. He was also present for the House vote Thursday and said he couldn't stay away as the final vote was taken.

"Today I just want to be a spectator of history," Tran said. "It is just so validating."

Jeff Moses and his legal husband, John Westerfield-Moses, of Minneapolis, got married in Iowa four years ago and were excited their home state is ready to follow suit. Their anniversary is Aug. 23, a few weeks after the Minnesota marriage law would take effect, and they're considering having a marriage ceremony here, too.

"Any excuse for a party," Jeff Moses said. "It's got to be on the 23rd or I will never remember the date."

John Westerfield-Moses said he knew this day would come.

"It was bound to happen," he said. "It was a train that was coming."

A more solemn display came from gay marriage opponents. Don Lee, of Eagan, placed a tombstone on the front lawn with the words "R.I.P. MARRIAGE 2013" but said he fully expected the bill to pass.

"The legislation being passed today is the end of marriage as we know it in Minnesota," Lee said. "It's a transformation from a forward-looking sacrificial institution to one focused on adult desires. .... People don't realize the damage they are doing. It's a fight against biology."

John Helmberger, head of the main opposition group Minnesotans for Marriage, told those on his side that conventional wisdom about the bill's fate shouldn't be trusted.

"Pray today for God to intervene," he said, addressing a smaller contingent of foes than were in the Capitol days earlier.

Like Thursday, there was a stepped-up security presence. State troopers were posted inside and out, and areas of the building were cordoned off to allow lawmakers to move freely amid the expected throngs.