To me, it's just a huge head-scratcher how a Southern Democratic candidate could underpoll the national one. Could it be merely a reflection of how much more appealing Chambliss is over McCain? That doesn't seem explanatory. The AA vote ignoring Martin doesn't seem to explain the consistent marginal difference either.
I guess Martin is pretty liberal for a Southern Democrat.
Well, Chambliss is polling better among AAs than McCain. I'm pretty sure Saxby's old CD was heavy with black population, so that could be making a difference.