Snopes says this is false:
New Orleans mayor Ray Nagin and Louisiana governor Kathleen Blanco refused President Bush's pleas to declare an emergency in Louisiana before Hurricane Katrina struck.
The timeline they provide... isn't in temporal order, so I've corrected the below (assuming they have their facts correct that is):
- On Friday (26 August), Governor Blanco did indeed declare a state of emergency for the state of Louisiana in advance of Katrina's making landfall in the Gulf Coast.
- On Saturday (27 August), Governor Blanco asked President Bush to declare a state of emergency at the federal level for the state of Louisiana.
- The White House responded to Governor Blanco's request that same day (Saturday) by declaring the emergency and authorizing FEMA "to identify, mobilize, and provide at its discretion, equipment and resources necessary to alleviate the impacts of the emergency."
- According to the St. Petersberg Times, Max Mayfield of the National Hurricane Center contacted government officials in Louisiana and Mississippi on Saturday night (27 August), not Friday night. [he apparently requested a mandatory evacuation due to Katrina's strength]
- According to the New Orleans Time-Picayune, President Bush's first communication with Louisiana governor Kathleen Blanco occurred on Sunday morning (August 28), just before a 9:30 AM press conference called by Governor Blanco and Mayor Nagin to announce the latter's mandatory evacuation order for New Orleans.
They have links at their page, so feel free to put any corrections or additional information in the comments.
9/19/05 UPDATE: Unfortunately, I didn't save off Snopes' page when I posted this, since it seems to have changed.
The current version has this as the assertion:
Louisiana governor Kathleen Blanco refused President Bush's pleas to declare an emergency before Hurricane Katrina struck.
Note that Nagin has been removed from what's above. And, note that the file was originally called "nagin.asp" but now it's "blanco.asp." They also appear to have added some text to the end.
There are copies of the original version here and here if anyone would care to do a diff. Note that the current version says its mod date is 9/9, but the first has a 9/8 mod date at the end of the excerpt.