Seems like it doesn't really matter much. There are very big name pro-abortion Catholic Democrats who regularly get reelected with Catholic votes and who still go to mass openly and receive communion without fear of reprisal from the church.
True, but I think that Dem loyalty is strong with many people i.e. 'my grandparents voted Dem, and so do I. They're the party of the working man'. People aren't quick to recognize change.
There's a thread at catholic.com focused on the Bishops, communication, and pro-abortion politicians running there now:
http://forums.catholic.com/showthread.php?p=1976397
I think it's fascinating reading, because there are so many knowledgeable and opinionated posters there (just like here).