It has been one year after the largely ineffectual response to the disaster of Hurricane Katrina. Despite the failures on all levels of government, it seems that history shows that Bush bears the full brunt of the blame for the failures. While Bush and FEMA do bear some blame for the aftermath, there are many failures that must be noticed if they are to be rectified. It may be politically helpful to pick a favorite scapegoat for political gain, however, lives are lost if all the lessons aren't learned. After action reports have been discarded for political talking points.
First, the United States is a grouping of 50 sovereign states. The president has no authority, absolutely none, to tell a governor what to do with their own resources. Governors cannot be selected by the President, they are not accountable to the President, and most importantly, they cannot be removed by the President. It may be simple to say "The buck stops at the top" but it reflects a sad lack of understanding of the US governmental system. Bush is responsible for some aspects of the aftermath, but Louisiana Governor Blanco and New Orleans Mayor Ray Nagin bear a good chunk of the blame themselves. They were elected to be sole stewards of their governmental assets and they utterly failed their constituents.
Second, it is important to note that the disaster plan was written by the State of Louisiana and the City of New Orleans alone. It was their plan. They are responsible for what their governments do leading up to a disaster, it was their responsibility to be prepared to deal with a disaster as much as possible, and it was their responsibility alone to deal with evacuation. FEMA responds after a disaster strikes; it is the local and state governments which must take action to mitigate the potential damage.
Third, the failure to call for an evacuation until virtually the last effective moment only maximized the number of people in harms way. Mississippi managed to handle the disaster effectively with minimal loss of life. Florida did as well. All the tales of horror came from Louisiana, and in particular, New Orleans. This was largely because those officials did not call for an evacuation. In fact, the President got on the phone to ask them to evacuate when it was clear they weren't doing so. An extra 24 to 48 hours would have been more than enough to evacuate every man, woman, and child from the New Orleans area.