More than 4.5 million Republicans (mostly... as there are open primaries and caucuses can include those of other affiliations) have expressed their preference for their party's 2012 presidential nominee in the first two months of a six month primary and caucus season. We know something about the religion of about nine in 10 of these participants (89% or more than 4 million) in exit polls (primaries) and entry polls (caucuses). Of those we can see in these data, 27% self-identify as Catholic representing 1.08 million participants to date. Of these Catholics, 49% have stated their preference in their primaries or caucuses for Gov. Mitt Romney (more than 530,000 votes).
The only caucus for which polling data are available was held in Nevada. There are no data available for Missouri's non-binding primary (this state will hold a caucus in March) or for the caucuses in Maine, Colorado, or Minnesota. Entry-poll data are available for the Iowa caucus but no question was used that would allow one to isolate Catholic participants. Sen. Rick Santorum did very well in most of these contests but even if he won every single Catholic vote in all of these contests he would still likely trail Romney by more than 200,000 votes and by double digits in percentage points among Catholic Republicans.