Obama to supporters: Vote early, just like me

So far, according to data released Wednesday, Republicans have an edge in two key states: Colorado and Florida. While states have yet to tally the actual votes, they do, when possible, report on turnout by party affiliation.

In Colorado, as of Wednesday morning, more than 325,000 early ballots had been returned, the Colorado Secretary of State's office reported, with nearly 39 percent belonging to registered Republicans and about 37 percent coming from Democrats. Another 24 percent came from voters affiliated with neither major party. As many as 80 percent of Colorado voters are expected to cast their ballots early, according to CBS News estimates. Absentee voting started on Oct. 15, and in-person early voting started this past Monday, Oct. 22.

In Florida, meanwhile, more than 925,000 people had voted by Wednesday morning, the Miami Herald reported -- already accounting for about 10 percent of the likely Florida electorate. Nearly 45 percent of those voters were Republican, while about 39 percent were Democrat and 16 percent were neither. While Republicans have a strong lead now, Democrats are expected to gain some momentum on Saturday, when in-person early voting starts. Absentee voting started on Oct. 2. CBS News predicts about 50 percent of Florida voters will cast a ballot before Election Day.

Republicans claim their early voting efforts will ultimately prove more valuable than the Democrats' efforts because of the voters they're targeting.

"While many of the Democrat ballots cast come from high propensity voters who would vote regardless, the Republican turnout operation has been focused on getting low propensity voters who would otherwise not vote to cast ballots early," Wiley said in his memo. "As such, turnout for the Romney-Ryan ticket on Election Day will remain as strong as expected."

For now, however, Democrats have a recorded edge in ballots cast in Nevada, Iowa and North Carolina.

More than 214,000 ballots have been cast in Nevada, the state reported Wednesday, with more than 46 percent coming from Democrats and about 37 percent from Republicans. About 60 percent of voters are expected to cast their ballots early in the Silver State, where absentee voting started on Oct. 17 and in-person voting started Oct. 20.