"If [President] Bush is falling apart so dramatically that he is in danger of simply vanishing, how come he's hanging in there in the polls?"
Bush has been in the low to mid-thirties for a very simple reason. In presidential polling, hard core partisans make up about 25% for each party. That is, in this case 25% of republicans are going to approve because Bush is a member of their party, and 25% of Democrats are going to disapprove because he isn't.
So, if we throw both those groups out as unable to be swayed, Bush gets about a 20% approval ratings from the remaining swayable respondents. That isn't exactly hanging in there.
Found via Atrios