Because, despite all claims to the contrary, the press is not liberal. All of the press (newspapers, radio, TV; with the exception of PBS and NPR) are in the control of a handful of giant media corporations. And those corporations are controlled by rich bastards. And rich bastards are, almost invariably, Republican. So while they sometimes champion really minor, inconsequential "leftist" causes to appear liberal or neutral or something, when it comes to the big issues, like calling out this administration, they are very very much friends of Bush and enemies of regular (i.e.: non-rich) Americans.