Also:
http://www.mrc.org/media-bias-101On the inherent one-sided liberal bias of the media, that is quantifiable in the number of stories reported, and 5 decades of polls of reporters on how they vote, and how they see a spectrum of issues.
As Marco Rubio said during one of the primary debates, answering a question about super-PAC influence, Rubio answered "Well of course, the greatest super-PAC of all is the liberal media..."
There is absolutely no question there is liberal bias in the media, and absolutely no question it negatively impacts Republicans. In 2012, in two separate debates Martha Raddatz and Candy Crowley BOTH intervened on behalf of the Obama/Biden ticket, and sided against the Republican ticket, in Crowley's case in a way that likely cost Romney votes, making Romney look foolish citing false facts in favor of Obama, and not correcting the error until a day later after the debate, when far fewer were watching and probably even knew of the CNN correction. Obama won with 51% of the vote, and the media did its part to bring him the very narrowest of victories.
