Because he is a raving nutbag moonbat who is highly corrupt. George Soros' group CREW named him the most corrupt member of congress! And Soros and CREW are ultra lefties.
Having this corrupt moonbat as the democrats majority leader would have been very helpful to the GOP.
But, but...there's plenty of those, like, uh...Nancy.
Plus, I truly doubt that Murtha will go quietly into the good night...and the Troops do not need that bastard given additional power.