“Whites have been leaving the Catholic church for some time, but the remaining ones have become less democrat than they were historically and have recently started voting pro-life.”
Evidence shows the opposite, at least in America.
The Protestants are losing people. Those who are left are less conservative. Catholics are becoming more conservative, and more conservative than their protestant brethren.
Go to that chart at the top of the page and look at how Catholics vote, and how Protestants vote.
You know that the catholic vote is a vote for democrats, you also know that that the Protestant vote is a vote against democrats, what effect do you think importing millions of more Catholics will have on the political issues that concern Christians in America?