The Baltimore Pride Festival was as much political rally as it was party Sunday, with supporters of same-sex marriage galvanizing a base of thousands to attempt to win a looming ballot fight.

Dozens of volunteers for both the Marylanders for Marriage Equality coalition and President Barack Obama's re-election campaign spread throughout Druid Hill Park on the final day of Baltimore Pride — the annual celebration of the city's gay and lesbian community — passing out stickers, selling T-shirts, registering voters and enlisting supporters. Their promotional materials were nearly ubiquitous.

"This is about people's lives," said Kevin Nix, a marriage equality coalition spokesman. "It's about people getting married and protecting their kids."

Since Gov. Martin O'Malley signed into law a bill legalizing same-sex marriage, the coalition has been working to make sure the bill stands. Maryland's Democratic-led General Assembly passed the law in March, but it does not go into effect until January 2013.

Opponents working to repeal the law have collected more than twice the 55,736 signatures needed for a November ballot referendum. The Rev. Derek McCoy, executive director of Maryland Marriage, the coalition collecting the signatures, said Sunday that 109,000 of those had been validated.

"We'll turn in an excess of 150,000, easy. We have participation from every county," McCoy said, adding that the issue is one voters, not politicians, should decide. "Marriage should be between one man and one woman. We're not hating on any group. We're just saying let's keep it going like it has been. It's worked for society for many years."

But supporters of same-sex marriage have been working events like Pride, packed with like-minded voters, and also farmers' markets, grocery stores, concerts and churches in hopes of winning more people to their side.

"It's never too early to start, and it's always too late," said Mark Yost, 31, of Mount Vernon, who wore a sticker promoting his support of same-sex marriage.

Lines formed at booths with festival-goers signing to become volunteers. The Marylanders for Marriage Equality coalition says its side has received a boost from Obama's announcement that his position has evolved and he now supports gay marriage.

"There's been a shift since the president came out in terms of favoring marriage equality," Nix said. "We're in a strong position heading into the fall."

The Obama campaign set up a booth at Baltimore Pride with a sign that read: "Obama Pride, LGBT for Obama."

There, Obama volunteer Robert Yochem pointed to a stack of documents collected at the event from people joining the president's campaign, which is seeking volunteers and donations. He said the campaign is confident the president will win Maryland but cares about recruiting volunteers for nearby Virginia and Pennsylvania and winning other key decisions in Maryland's election, such as the same-sex marriage vote.

"They value Maryland very highly," he said of the Obama campaign.

Public opinion in Maryland is split on same-sex marriage — a recent poll indicated that 49 percent of voters were in favor and 47 percent against.

Similar same-sex marriage measures are expected to appear on ballots this fall in Maine, Minnesota and Washington. Opponents have won nearly every time the question has gone to the ballot. Earlier this year, North Carolina voters approved by a wide margin a constitutional amendment banning gay marriage, becoming the 30th state to do so.

But supporters in Druid Hill Park were confident Maryland would break that trend.

"Maryland is a lot different state," Yost said. "Maryland is a lot more liberal state."

Six states and the District of Columbia now issue marriage licenses to same-sex couples.

luke.broadwater@baltsun.com

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