Thus far blue-collar urban Catholics seem to be voting for Romney more than Santorum. Perhaps that will reverse itself in Pennsylvania, but I somewhat doubt it.
Yes, that was my thought, and the issue is whether the home town boy (well his hometown is across the state but whatever), can use the home field advantage to reverse that. Does the Philly versus Pittsburg rivalry have any relevance here? Philly area voters tend to have a certain disdain for the western PA types who cling to their guns and religion, as it were (obviously less so among Pubs). And it may depend in part as to just how much the Pubs want to avoid not having a nominee by June, which is a specter that terrifies the GOP establishment, and is now leeching into the conservative websites and blogs.
Those are my rambling ruminations anyway.