MILWAUKEE - With just 60 hours until voters begin heading to the polls, the Obama campaign is heralding the mobilization of a massive battleground organizing operation - unprecedented in size and scope - that it says will be a decisive factor in the outcome on Nov. 6.

It is a "ground game unlike any that American politics has ever seen and much bigger than we did in 2008," Obama campaign manager Jim Messina told reporters on an evening conference call.

"Our get-out-the-vote effort - built over years and running at full speed today - is the reason President Obama will be re-elected to a second term," said Obama national field director Jeremy Bird.

In a memo detailing the operation, the Obama campaign says it has more than 5,000 get-out-the-vote "staging centers" (or, "hyper-local Obama campaign hubs") going online across the battlegrounds this weekend and coordinating volunteers for more nearly 700,000 canvassing shifts.

Aides said the campaign's biggest advantage over Republicans was in registrations: 1.7 million voters this cycle - twice as many as it did during the 2008 campaign.

Of those voters, officials said, 28 percent (345,000) have already cast their ballots.

Read the full OFA memo here.

"The math is clear: our opponent is losing among early voters in nearly every public poll in every battleground state, meaning that if these public polls are right, he would have to win 65 percent of the remaining votes in North Carolina, 59 percent in Iowa and Colorado, 58 percent in Nevada, 55 percent in Florida and Ohio, and 52 percent in Virginia and Wisconsin," said Bird.

The campaign is also stressing the quality of its voter contacts compared to the Republican operation, which has relied on robo-calls on auto dialers and other forms of non-personal outreach.

"At the start of GOTV weekend, our volunteers have made more than 125 million personal phone calls or door knocks. These do not include robo calls on auto dialers, mail, literature drops or any other form of non-volunteer, non-personal contact," Bird said. "They are personal outreach conversations. Many have historically favored quantity over quality. We do not. In each conversation we have with the voter, our goal is to make a difference."

Republican officials dismissed the difference in type of contact, pointing to several recent public polls that show both campaigns are roughly on par with percentage of voters who said they had been contacted.

In the latest ABC News/Washington Post tracking poll, for example, 29 percent of likely voters said they had been contacted either by phone, in-person or online by the Obama campaign compared to 27 percent of voters saying they had been contacted by Romney.

Republicans also insist that the early vote totals touted by Team Obama include large numbers of high-propensity voters, or those who would have voted anyway, thereby not representing a net expansion in the electorate for Democrats.