NEW ORLEANS - Under pressure from President Bush and other top federal officials, the mayor suspended the reopening of large portions of the city Monday and instead ordered nearly everyone out because of the risk of a new round of flooding from a tropical storm on the way.
''If we are off, I'd rather err on the side of conservatism to make sure we have everyone out,'' Mayor Ray Nagin said.
The announcement came after repeated warnings from top federal officials - and the president himself - that New Orleans was not safe enough to reopen.
Among other things, federal officials warned that Tropical Storm Rita could breach the city's temporarily patched-up levees and swamp the city all over again.
The official death toll from Hurricane Katrina reached 973 across the Gulf Coast, with the number in Louisiana alone rising by 90 to 736.
The mayor reversed course even as residents began trickling back to the first neighborhood opened as part of his plan, the less damaged Algiers section.
Nagin wanted to reopen some of the city's signature neighborhoods over the coming week to reassure the people of New Orleans that ''there was a city to come back to.''
But ''now we have conditions that have changed. We have another hurricane that is approaching us,'' Nagin said. He warned that the city's pumping system was not yet running at full capacity and that the levees were still in a ''very weak position.''
The mayor ordered residents who circumvented checkpoints and slipped back into still-closed parts of the city, including the French Quarter, to leave immediately.
Nagin also urged everyone already settled back into Algiers to be ready to evacuate as early as Wednesday. The city requested 200 buses to help if necessary.
Louisiana Gov. Kathleen Blanco, in a televised address Monday, also urged residents of coastal southwest Louisiana to be prepared to leave. More evacuees would strain the shelters in Texas, she said, so she urged people to head for central and northern Louisiana instead.
''We will pray that Rita will not devastate Louisiana, but today we do not know the answer to that question,'' Blanco said.