What about just being fed up with people who use their ideology to obstruct progress? I think the reason liberals appear to be prejudiced against conservatives is that conservatives have no solutions to offer, yet they interfere with those of us who do.
Essentially, conservatism is fear. Fear of the future, fear of the unknown, fear of progress, fear of change, fear of people who are not like them, fear of people who do not agree with them. Fear so deep they create imaginary beings they can talk to for relief. Are we really prejudiced if the group’s stated mission is to stop the rest of us from improving our lives?