Dr. Lyle Rossiter is a forensic psychologist who has published a book claiming that liberals are mentally ill and purports to trace the psychological causes of liberalism. And on an AFA radio show he claims, as wingnuts love to do, that the American public is on their side and we’re on the verge of a rebellion against liberals in power.
There’s actually a good deal of psychological data on what mental and emotional tendencies lead us to become liberal or conservative. Liberals are generally more open to new experiences, more comfortable with ambiguity, less likely to go with the herd, more likely to embrace change, and so forth. Conservatives tend to be more closed to new experiences, want things (and therefore usually interpret things) to be in absolute black and white, more easily subordinate themselves to authority and much more prone to aggressively opposing those they view as being of a different tribe. I highly recommend Robert Altemeyer’s work on this subject, but he’s hardly the only one.