here is bias from both sides. Dan Rather, Chris Matthews and Katie Couric,
I must admit I don't see with these. Besides Chris Matthews is also an Opinion column and he often pisses liberals off in it. MSNBC in general isn't a news source they are a Entertainment network. "The Place for politics."
I would argue however they aren't pushing a Liberal Agenda either just an anti-republican one. MSNBC has distortion that is pushing an entertainment agenda for certain sponsors.
As for Katie Couric I still can't see the "bias" in her interviews she asks questions potentially hard ones and let's the responses happen that's what an interview is. Bill O'Riley and Ed Schultz on the other hand talk over and attempt sway the interview. It could just be me.
My conclusion
Fox is pushing a corporate agenda and MSNBC an Entertainment one for the sake of sponsors.
As for CNN well.... They just report whatever is popular.