Mississippi was somewhat close in 2008 and 2012 due to ultra-conservative voters not supporting John McCain and Mitt Romney due to religious differences and ideological disagreements and higher Black turnout for Obama.
There's really no evidence of either of these two things. The Tea Party types may not have loved Romney, but they hate Obama SO much more that they all came out and voted for him.
Demographic drift is the reason Mississippi has fallen from the 10th or so most Republican state to the 17th or so. Black birthrates have been higher than white birthrates for decades, and white emigrate to other states at a much higher rate than blacks. Just from 2000 to 2010 Mississippi's white % fell by 2.5 percentage points (I believe that number includes white Hispanics, so the white non-Hispanic rate probably fell slightly more than that), and that trend will continue and probably quicken. I would expect Mississippi to only barely be majority white by 2030, if not plurality.
Also, remember that even Kerry won the under-30 vote in Mississippi in 2004 (he won it in about 30 states IIRC). That's now the under-40 vote in Mississippi. Sure, some of those under-40s have found Jesus and are now good repentant Baptists, but I don't think that's a very high percentage. On the contrary, old white Mississippians are much more Republican than what is typical of their age group. This is a fascinating article, although it might be a little too optimistic (from my perspective): http://ablogofrivals.wordpress.com/2012/11/29/mississippi-blues-the-emerging-democratic-majority/
So should we expect Mississippi to go Democratic before Texas? How about Georgia?
