President Bush says federal officials have "deep concern" about Tropical Storm Rita causing more flooding in New Orleans.
In remarks at the White House Monday, Mr. Bush said the U.S. Army Corps of Engineers fears that heavy rain could cause the city's recently-repaired levees to break again.
Much of New Orleans sits below sea level, and the levees' failure during Hurricane Katrina put 80 percent of the city underwater.
Weather forecasters say Tropical Storm Rita could become a hurricane and move into the Gulf of Mexico south of New Orleans later this week.
The president said New Orleans officials must be "realistic" about bringing people back to the city before it is safe.