Now that's some "Souls to Polls" in Georgia: 68% of Sunday voters were African-American
— Michael McDonald (@ElectProject) October 27, 2014
An academic at the University of Florida is following early voting around the country.
http://www.electproject.org/...
Nunn's campaign and Michelle Obama previously said we need to turnout 137,000 total votes or 50 voters per precinct from our midterm drop-off voters--those that didn't vote in 2010 but voted in 2012. To be safe, a campaign memo said to aim for 200,000 new voters, assuming a total turnout of 2.7 million.
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Update: All numbers now reflect new data available on 10/28.
Original title was: "With 1/6 of votes in, we're probably 1/4 (conservatively 1/6) of the way to winning"
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Early vote (EV) numbers show that 440,554 522,364 have voted so far, or 16.3% 19.3% of 2.7 million.
Participation, including Sunday's Monday's returns, has African Americans (AA) at 30.13%, whites at 59.85% and 8.89% unknown.
FYI, some voter demographics are unknown because the professor's oldish voter file does not include new registrations from 2013 and 2014. During these last years, AA representation among registered voters increased from 28.7% in 2012 to 30.0% today.

If you (conservatively) assume that 1/3 of "unknown" voters are AA, then 38.0% of these new midterm voters are AA (.333*29.3+28.2). There's around a 90% level of support for Michelle Nunn, resulting (i.e. .38*116,883*.9) in 39,974 'new' voters.
Right there, that's 29.2% of the 137,000 needed or 20.0% of 200,000. And I can attest that the ground-game is trying to mobilize ALL of our midterm drop-off voters.
We need volunteers to pull this off. The GOTV infrastructure is in place.