Make no mistake about it. There is no liberal media bias. There never was. There's real news and then there's Fox "news."
When Fox first came on the air, they screamed liberal media in order to throw the spotlight off what they planned on doing: Undermine the Democratic administration (of Bill Clinton at that time) with propaganda, smear campaigns, and fear-mongering, while supporting any future Republican ones. That's their one and only mandate and everyone knows it.
President Obama, in a wide-ranging interview with CNBC's John Harwood that covered the economy and the turbulent Iranian election, took a shot at Fox News when asked about media coverage of his young administration (H/t Politico for the video clip):
Watch the full interview HERE.