Early voting has edged past the 1 million mark, and while the numbers are still too small to draw sweeping conclusions, so far they show a Democratic advantage.

“Registered Democrats are voting at levels that are either equal to or exceeding the 2008 elections as a percentage of votes cast so far,” said political science professor Michael McDonald, who heads the United States Elections Project at George Mason University, which monitors election data.

Many states don’t supply party registration as part of early voting results. But information from those that do suggest that reports of waning Democratic enthusiasm in 2012 may be overstated, McDonald said. In Iowa, the state with the largest share of the electorate voting early (14.2 percent) Democrats have a nearly 2-to-1 edge (52 percent to 28 percent) among the 220,000 early votes cast. The margin is narrower when it comes to absentee ballot requests (48-30) and Republicans have gained ground there in recent weeks.

In Florida, Republicans have a four-point margin in party registration of early voters (44-40), but that is down considerably over the 12 point edge they enjoyed in 2008.

Ohio, the all-important battleground state, is harder to read because partisan registration is not part of the information reported. County-by-county numbers show increased early voting activity in both heavy Democratic and Republican areas. In Franklin County, home to Ohio State University, where the Obama campaign has pushed hard to organize students, 11 percent of the electorate (62,000) has voted early.

McDonald said that overall early voting in the U.S. will likely exceed 2008 levels, when about 30 percent of the electorate cast early ballots.

“The unknown question here is whether the Obama campaign is simply harvesting votes they would have gotten anyway or are actually activating people who would not have otherwise voted," McDonald said. "It's probably a combination of the two."