According to the National Response Plan, local and state officals are to handle the initial crisis and federal assistance to be delivered when regional resources prove inadequate.
No city in america stockpiles food, water, and port-a-potties to be used in case of emergency, nor should they. They assume a day after a disaster the national guard, fema, and the U.S. military will be in there providing all that stuff. It is more efficient that way.
As for the evacuation, the major begged everyone to leave. Those that didn't went to the Superdome as planned. The Superdome worked perfectly for the initial storm.
As for partisan politics. This country is really just the republican union vs. the democratic union. Both are full of jerks.