From a piece by Robert Dallek in the Washington Post:
Polls showing President Bush's approval ratings in the 20s and 30s and a New York Times survey last month reporting that people across the country are eager for an end to the current administration suggest that this nation has a problem it's going to have to live with for the next 17 months -- a failed presidency that won't reestablish its credibility with a national majority.
The political argument against Bush's continuing tenure is not frivolous. There are good reasons to see him as a failed president whose remaining time in office will be unproductive at best and destructive to the country's well-being at worst. But given the constitutional rules by which the presidency operates, there is no serious prospect of removing him from office.