Sure, it's great to blame Barack Obama for Jim Martin's loss. After all, Barack Obama totally won the state of Georgia in the general election. And a mere word from the man who clearly, as a black guy, has total control over all African-American population, would totally have turned out the additional 350,000 or so African-American voters necessary to put Jim Martin over the top.
Plus, he's the president-elect. We gotta blame him!
However, as important as blaming Obama is, I think there's a more likely reason for Saxby Chambliss' victory:
He has a way with the ladies