Can't Blame Obama on this One
The Hill claims that a light turnout, especially among AA voters, is one of the reasons Martin lost. But they also said Obama wasn't willing to go and campaign directly for Martin.
Obama is smart politically, and I hope he chose not to go campaign for Martin out of spite (Martin was a JRE supporter) but rather he is going to be different from most Dems and not campaign any further; instead he will focus on governance. Often I thought Bill Clinton overdid the campaigning bit.
Therefore, I don't blame Obama for not going down to Georgia. Too much work to be done and needs to have his cabinet picks almost completely in place by January 20th. He has to appear to be ready from the get-go.
I think there is election fatigue in general, and that's why Martin lost. Georgia is a deep red state after all.