Nate Cohn at NYT’s New “The Upshot:”

It is impossible to discuss Mr. Obama’s weakness among Southern whites without mention of race. It is surely a factor, and perhaps even a large one. Mr. Obama performed significantly worse than John Kerry among Southern whites, even though both were Northern liberals and 2008 was a far better year for Democrats than 2004. (The estimates are derived from census and exit poll data). And the pattern of white support in the 2012 presidential election is an eerie reversal of post-Reconstruction presidential elections, when Jim Crow laws rendered blacks ineligible to vote and Democrats won the so-called Solid South by similar margins.

But it is hard to know the extent to which racism is responsible for Mr. Obama’s weakness. After all, Mr. Obama is not the only Democrat to perform so poorly in recent years. Some white Democratic candidates, like Virginia Gov. Terry McAuliffe, have done worse than Mr. Obama among Southern whites. And Mr. Obama’s losses are part of a longer-term trend. Mr. Kerry, for instance, performed worse than Al Gore, who even fared worse than Michael Dukakis among Southern whites.