I often hear that Catholics have unity, while Protestants are divided (the old forty thousand denominations canard).
However, I always reply that Catholic unity is outward (ritual and authority structure), while conservative Protestants find unity in doctrine.
A new survey confirms what I have said.
Note the split between "Mainline" (aka Liberal, lower right) Protestants and "Evangelical" (conservative, upper right). We also see that Catholics are not identified with any political ideology (they are disparate in their application of doctrine to practice).
It's interesting that "Other" tend toward the lower left (except for Muslims, Hindus, and Jews).
It's as I have said - conservative Christians tend toward conservative politics.