You don't think they are tools of some kind, used by clever Grima Wormtongue-like advisors? Or advisors who have some kind of hook on them, like blackmail of some kind?
I know that one should not ascribe deceit when simple stupidity will do, but it's so hard to imagine anyone as primally stone-stupid as Blanko and "I am not a drug addict" Nagin. Even any ordinary third grader would have made better decisions.
I don't think there was a plan from the start, I think that the Democrats saw the incompetence of their own and always ready and willing to blame anything on Bush they started up the spin machine.
I don't think that Nagin has ever been in control of anything. He took his marching orders from Blanco and went along with her recommendations. Then, when things were going really bad he woke up and realized if he didn't say something quick he was going to be left holding the bag.
I believe that Blanco also was never really in control. I think she was consulting other Democrats like Mary Landrieu on what was the best political thing to do, not what was the best for the people of Louisiana and New Orleans. They were more worried about tourist dollars and being sued, so they weren't gearing up when they should have been for the hurricane and worrying about what needed to be done to protect the people.
Bottom line, if there is any chance to blame anything on Bush, you just do it. The media and the liberals aren't going to hold you accountable for anything you have done or said anyway.