Santorum doing well in the Gulf Coast is interesting. Maybe for once he's actually doing well among Catholics? That would make a sort of sense, since in the South Catholics are much more "the other" than in the Rust Belt. That would be a very good sign for him in Louisiana.
Yes, and some of those Catholics are well, yes, you guessed it - Coonass Cajuns. Cajuns loved being called coonasses by the way. It is a term of endearment.
There's a huge difference between rural Catholics and urban Catholics in GOP primary voting. I would suspect the main reason why Romney has done well with rust belt Catholics overall is that Catholics are more likely to live in urban areas. If you look at the Catholic counties in the rural parts (of Ohio at least and Michigan shows this somewhat too) Romney lose to Santorum pretty badly.
That's my guess anyway.
