These numbers out of the South make the national polls make sense...
On the other hand, Obama has a massive lead in states like New York, which offsets some of the gains Romney will make in the South and should be reflected by national polls as well.
Actually no, using 2008 as a baseline, if Obama maintains those leads in NY, IL etc, but performing like a normal Dem in the Midwest and the South turning hard(er) against him - then there's been a shift away from Obama, that isn't being compensated for.