I think self-righteousness is a HUMAN trait, most common in those who think they have a moral or intellectual superiority.
Those who bother to draw attention to their superiority are generally those who can be quickly labeled as "liberal" or "conservative".
Also, those who bandy around terms "liberal" or "conservative" are generally not doing so as a term of endearment, thus placing themselves in "superiority".
We can speak in general terms, as the original question is posed, and my answer is "Yes"
And, regrettably, as we speak of more specific subclasses within the two original genera, I still say "Yes".
Perhaps a more telling question is "What are some of the characteristics of self righteous people?"
We then can categorize those characteristics as liberal or conservative traits, and after a significant sample, draw conclusions....
Soakers, intellectually bored.