The modern practice of politics is, too often, the art of attaching blame. Whether or not a politician is popular depends, not on his or her policies or tactics, but on the way their tenure is framed by the political media. Barack Obama rode to the White House on a wave of positive feeling; his campaign was more positive than negative and the media embraced his personal story. Once in office, he experienced the other side of that media embrace; the side where the media grows tired of positivity and embraces the vitriol and controversy that sells ads.
There is no room for quitters or whiners in politics. It is for that reason that Sarah Palin should go away, and Robert Gibbs should stay away from lame criticisms of left-leaning media. The public is fickle; they may not understand all of the intricacies of policy, but they know weakness when they see it. You can blame media conspiracies for only so long before the public realizes that you are simply searching for an excuse. When it comes to scapegoating, the public is prepared to accept only that application of blame that is sanctified by the media, not directed at the media. Politicians that are successful over the long term happen on that success by virtue of their ability to get the media to sanctify their scapegoating.