That's how Katrina became a GOP debacle. It was a Dem mayor who failed to fully evacuate the city, and a Dem governor who waited two days to invite FEMA in. But because the stranded people in New Orleans were (in Wolf Blitzer’s words) “so very black” the meme was immediately created that Bush didn't care about them because of the color of their skin. Bush was afraid to fight back because the howls of racism grew louder each time, as he would be accused of attacking a black mayor and black residents for not getting out of there themselves.
The only way for McCain to fight back on this is to be willing to weather a “racism” charge. He may decide, like Bush, to just keep his mouth shut and take the blame for the debacle rather than risk such a charge. Does anyone here think McCain has the political nerve to say that minorities who aren't financially qualified for a home loan shouldn't get them?
I don't think that that would actually be that hard to explain (such that even Obama would understand it). Lowering the standards for financing a house allowed people (not just the minorities) to afford a house that they shouldn't have bought. This artificially raised the value of housing (the bubble that recently burst). If minorities were assisted in purchasing housing within their means, they still would have had home ownership and, quite possibly, would still be in them.
The Freddie Mac and Fannie Mae game, in my opinion, was a pyramid scheme that would have continued working if the housing market continued to experience strong growth. Everyone was betting on a house being worth a lot more next year and would have covered the bad debt. When the housing market eroded, the rest was just a matter of time.