My feeling on the matter (having been through several ridiculous Fark comments threads on the subject) is that there's a fair amount of blame to go around at all levels of government in and above New Orleans, and that it's mostly partisan leanings that are making people focus either solely on the federal government (if you want to bash Republicans) or solely on the state and local levels in Louisiana and New Orleans (if you want to bash Democrats). There probably are people who have non-partisan reasons for focusing on one level of government to the exclusion of others, but my gut instinct is that most people who do so are doing so for partisan reasons.