Public Policy Polling (PPP) released a survey [pdf] taken in Louisiana. From the republican portion of the sample:

[….]

Q2 Who do you think was more responsible for the poor response to Hurricane Katrina: George W. Bush or Barack Obama?

George W. Bush ……………………………………… 28%

Barack Obama………………………………………… 29%

Not sure …………………………………………………. 44%

[….]

….PPP surveyed 721 Louisiana voters, including an oversample of 274 usual Republican primary voters, between August 16-19, 2013. The margin of error for the overall survey was +/- 3.7% and +/- 5.9% for the GOP portion….

The crosstabs are interesting.

In case you forgot, Hurricane Katrina occurred in August 2005, over three years before Barack Obama took office as President.