James Taranto, in the Wall Street Journal, explains where all the incivility is coming from.

“Terrorist,” “racist,” “uncivil,” “insane,” the list goes on–in this context, these words have no real meaning. They are mere epithets. The Obama presidency has reduced the liberal left to an apoplectic rage. His Ivy League credentials, superior attitude, pseudointellectual mien and facile adherence to lefty ideology make him the perfect personification of the liberal elite. Thus far at least, he has been an utter failure both at winning public support and at managing the affairs of the nation.

Obama’s failure is the failure of the liberal elite, and that is why their ressentiment has reached such intensity. Their ideas, such as they are, are being put to a real-world test and found severely wanting. As a result, their authority is collapsing. And if there is one thing they know deep in their bones, it is that they are entitled to that authority. They lash out, desperately and pathetically, because they have nothing to offer but fear and anger.