The Washington Post has a poll which reports on how evacuees from New Orleans regard the President, Governor and Mayor.
Among this sample 70% disapprove of Bush's handling of the situation and only 15% approve. Blanco and Nagin fare somewhat better (58% disapprove - 27% approve and 53% disapprove - 33% approve respectively).
Bad news for Bush, huh? Well, not entirely. The sample is 93% black and 92% urban. The Democrat Party is proud of receiving around 90% of black votes - more if you restrict your sample to poor, urban blacks. So there is another way of reading this poll. If it had chosen to do so, the Post could have headlined this poll with "Bush support doubles" or "Two thirds of Democrats desert Blanco, Nagin".
No doubt the Republican Party has a long way to go to boost its support among black voters. But this poll certainly does not justify claims that the Party is moving backwards.