In this Sept. 9, 2011, file photo, Mellissa Brown, right, a volunteer for Organizing for America, shows Barbara Ferret, center, of Westerville, Ohio, where to sign a petition, in a ballot repeal effort by opponents of the Ohio's new elections law.

Supporters of President Obama in Ohio, a key battleground state, have scored what is seen as a significant victory for maximizing Democratic voter turnout ahead of the 2012 presidential election.

Obama campaign volunteers and a coalition of Democratic-aligned advocacy organizations gathered more than 318,000 signatures to effectively block new Republican-sponsored voting restrictions from taking effect through the next year, the groups announced today.

“It’s a victory for organizing,” said Brian Rothenberg, who led the fight against the new rules.

A law signed by Republican Gov. John Kasich in July would have shortened by two weeks the early voting period by mail and in-person, eliminated early voting in the three days before the election, and ceased automatic mailing of absentee ballots to all registered voters in the state’s largest counties, among other measures.

Those changes to voting rules will now be put directly before Ohioans in a ballot measure, assuming at least 231,000 petitions are first certified by the secretary of state. The deadline for the signatures was Friday.

“A lot of the people who supported President Obama in 2007 and 2008 understand that the more open and accessible our democracy is the more they can participate in it,” said Obama for America state director Greg Schultz, explaining why the organization got involved in the petition campaign.

“If you look at the history in Ohio, when voting opportunities are expanded, Democrats win,” he said.

In 2008, some 1.4 million Ohioans – or 30% of the total number of voters – cast ballots before Election Day, according to the United States Election Project at George Mason University.  Democrats and Obama are widely seen as benefiting most from that extended early voting period.

“Instead of one Election Day, there’s 35 election days,” said Seth Bringman, communications director of the Ohio Democratic Party, in an interview earlier this month.  “The Obama campaign took advantage of that in 2008, and went into Election Day with a wide lead because of the early vote margin that had been acquired prior.”

In fighting to preserve the election law changes, Republicans have called the early voting process too long, too costly for budget-strapped counties and too prone to fraud and abuse.  And today they cried foul over what they called a politically motivated effort.

“Where Ohioans are fighting for a chance to ensure fairness at the voting polls, the Obama reelection machine sees an opportunity to suppress Republican votes — plain and simple,” said Ohio Republican Party spokesman Chris Maloney.

“Political partisanship and reelection prospects should not play a role in ensuring that each and every Ohioan, regardless of where they live, receives a fair and equal opportunity to vote.”

Ohio, which Obama carried with 51 percent of the vote in 2008, is considered a must-win in his bid for a second term. No president since John F. Kennedy in 1960 has won the White House without winning Ohio.

A Quinnipiac University poll released today shows 53 percent of Ohio voters disapprove of the president, while 51 percent say he does not deserve a second term — signs the state will likely remain a hotly contested battleground for Obama next fall.