That’s what National Journal says, anyway. The magazine uses an unorthodox method of determining how difficult it will be for Democrats to pick up a Republican seat, and of the 12 states they look at, Georgia is the most difficult.
In a nutshell, they look at the number of registered voters, and multiply it by a factor to get the expected turnout in the general election. They then determine how many votes will be needed to win, and the number of ‘reliable’ Democratic voters that will vote pretty much no matter what. The difference is the number of additional voters that will be needed to cast Democratic votes in order to guarantee a win. In the case of Georgia, that number is 663,699 additional votes.
How do they get there? One method, according to the story, would be to use direct mail to motivate the potential voters. At a cost of $47 per vote, that’s where they come up with the $31 million plus number. Another option would be to get volunteers to go door to door, canvassing for votes. But not every door knock gets you someone to talk to, and not everyone you talk to is going to vote. The story estimates it would take 1,548,631 hours of volunteer time to guarantee the number of votes needed to put Michelle Nunn in the Georgia Senate seat.