In New York Magazine, John Heilemann has a piece on the MSM turning on McCain:
I have sat across from Chris Matthews enough times now, participating in that psychotropic ritual known as Hardball, that I thought I`d heard it all - but then the other night he uncorked a doozy that actually rendered me speechless. (No, that is not a misprint.) "Let`s start with John McCain," he said to me on the air shortly after the first presidential debate between McCain and Barack Obama. "Do you think he was too troll-like tonight? You know, too much of a troll?" I laughed. "Seriously," Chris went on. "Do people really want to put up with four years of that? Of [him] sitting there, angrily, grumpily, like a codger?"
As both a media figure and a human being, Matthews is sui generis - and yet what made his comments so remarkable was how unremarkable they were. In the past several weeks, the shift of press-corps sentiment against McCain has been stark and undeniable, even among heavies such as Matthews long accused by the left of being residents of the Arizonan`s amen corner. Jonathan Alter, Joe Klein, Richard Cohen, David Ignatius, Jacob Weisberg: all former McCain admirers now turned brutal critics. Equally if not more damaging, the shift has been just as pronounced, if less operatic, among straight-news reporters. Suddenly, McCain is no longer being portrayed as a straight-talking, truth-telling maverick but as a liar, a fraud, and an opportunist with acute anger-management issues.
[How John McCain Went From Maverick to Crank, October 5, 2008]
Of course, he was always like that, but they didn`t feel like pointing it out as long as he was a "maverick"—a loose cannon aimed at the Republican Party.
But as Mickey Kaus points out, none of those people were ever actually McCain supporters—they`re Democrats. Once McCain became the Republican nominee, opposed to Obama, the "promised prince" then McCain`s days as a media idol were over.