This shouldn’t be a big surprise.
Rothman and Lichter researched and wrote a book on American radicals, “The Roots of Radicalism: Jews, Christians and the Left” back in 1982. They discovered that the Christian component of the Left were largely Catholics.
I didn't know about the book, I stumbled across this truth about 3 or 4 years ago, by looking at voting data, and then digging deeper, and farther back, it is shocking.
Romney winning 48% of the Catholic vote, is one of the greatest republican margins of all time.
This current period of 1972 to 2012, is as good as it gets, it was the glory days of the GOP sometimes winning a slim margin of the Catholic vote.