Down here in north suburbs of Georgia I go to several churches. They are mostly very conservative. The one in this town Woodstock because of prayer vigils in front of abortion center, closed it down last year. Also the bishops letter against Obama Care was read at all churches in June and July.
From my experience the most hardcore conservatives are the ones who I usually pray prayers in chapel Holy hour or before or after mass. I never met a devout prayer who was not conservative.
I hope this can give you an accurate view.
The polls are of Catholics who identify as Catholic, and who have been baptized into the Catholic church.
If they identify as an ex-Catholic but still consider themselves Christian, then they are counted as Protestants, as are Christians that don't have any church, or even baptism.
I have read that the more often a Catholic attends Mass, the more likely said person attends, the more likely said person is politically conservative. I've also been told that only about 10% of Catholics attend Mass at least weekly. Putting the two together, they say that the number of "real Catholics" in this country is no higher than 7 million (i.e. not the 70 million or so that the USCCB reports).
But that's the maximum. If your 20-30% number holds true (and I believe it does), the number of (reliably) politically conservative, observant Catholics actually numbers around 5 million. This doesn't surprise me. It's one way to understand why Crisis Magazine would report this about The Mythical Catholic Vote: The Harmful Consequences of Political Assimilation:
Unfortunately enough, Catholics are largely indistinguishable from non-Catholics and, despite a few pundits, no, there really is no “Catholic vote.” This obvious conclusion—clear enough from the fact that the vote for the winning candidates in the last national election was approximately the same for Catholics and non-Catholics—has serious current implications....