A coherent case simply cannot be made here to pin this on Bush. Of course, there is going to be a hardcore Bush-hating group that thinks that he personally remote-controlled the airplanes on 9/11, and that he is the source of all ills in the world. But they are to be disregarded at the onset.
There just aren't very many angles to manipulate the information surrounding the Katrina disaster. So much of it was all out in the open. You can create any back-story you want to push an agenda for something that goes on behind closed doors. Like with the Iraq war - there was unquestionably enough meat (by the nature of war) for the MSM and others to put a neat little anti-Bush outrage story out. Little of it is backed up by fact, but instead makes use of ambiguity to push an agenda.
Now Katrina. Try as they may, there is too little ambiguity available to put a neat little tale together to Bush-bash with. I'm in Canada, surrounded by virulent anti-Bush folks (coworkers, friends, family), people who are on the 'Cindy' side of Iraq. But not ONE of them I have talked to blames Katrina, or the (generally) poor handling of NO afterwords, on Bush.
It is just too difficult to bend perceptions that far from reality here.
Well, I am constantly amazed at some people's ability to do just that :-)