David Goldman/AP Photo

If Mitt Romney is going to turn things around, he needs to start soon because this election may be effectively over weeks before November 6.

Why? In many of the battleground states, voting starts before election day.

Waiting for a game-changing moment at the debates is risky. In Iowa, polls open for in-person voting on September 27 - one week before the first debate. Ohio's early voting also starts before the first debate. Several other states start voting before the last debate (October 22).

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In North Carolina, absentee ballots have already been available for over a week.

In 2008, 31 percent of ballots were cast before election day. Time's Michael Crowley estimates that number could rise to 36 percent this time around.

The campaigns, of course, are well aware of this and are spending heavily on get-out-the-vote operations that are already well underway.

Here's a list of early voting dates in the top battleground states and the state-by-state percentage of the that voted early in 2008:

North Carolina

9/7- absentee ballots first available.

10/18- first day of in-person early voting

2008: 2.4 million out of a total 4.3 million votes cast. (56%)

Wisconsin

9/20- absentee ballots first available

10/22- first day of in-person early voting.

2008: roughly 16% of Wisconsin voters voted through in-person absentee voting.

Virginia

9/21- absentee ballots first available

Virginia does not allow in-person early voting.

2008: 506,672 out of a total 3,752,858 (14%)

Iowa

9/27- absentee ballots first available AND first day of in-person early voting

2008: 56292 out of a total 157845- 36%

Florida

10/2- Absentee ballots first available

10/27- first day of early voting***** (This is still being disputed in court, there's a motion to extend the early voting days from 8 to 14)

2008: 4,377,774 out of a total 7,640,319- 57.3%

Ohio

10/2- Absentee ballots first available AND first day of in-person early voting.

2008- 1,744,753 out of a total 5,773,777- 30%

New Hampshire

10/8- absentee ballots first available

State does not allow in-person early voting.

N/A

Colorado

10/15- Absentee ballots first available

10/22- 1st day of in-person early voting

63% voted by mail-in ballot (this is the only way CO classifies when votes were cast in their archives)

Nevada

10/17- absentee ballots first available

10/20- first day of in-person early voting

2008- 561,772 out of a total 970,019- 58% of vote came in early in person

With research by ABC's Elizabeth Hartfield.