The White House quickly arranged another trip by the president to the Gulf Coast on Monday, while he and Laura Bush paid a thank-you call on the Red Cross's disaster operations centre on Sunday and announced a White House blood drive.
"The world saw this tidal wave of disaster" hit the Gulf Coast, Bush said at the Red Cross centre. "Now they're going to see a tidal wave of compassion."
Secretary of State Condoleezza Rice, who was sent to her native Alabama, was among four cabinet secretaries and other high-ranking administration officials who fanned who out across the storm-ravaged region on Sunday.
Six days after Katrina lashed much of the Gulf Coast, and five days after embankment breaks drowned New Orleans and turned it into a place of lawless misery where thousands are feared dead, Homeland Security Secretary Michael Chertoff said military personnel and National Guard troops had secured the city and ensured that those still stranded could be moved out.
But he said significant challenges remained, including how to care for the people being relocated.
The Bush administration is facing
criticism over its slow response
"We are still in the middle of the emergency," Chertoff said on CNN's Late Edition. "We are moving the city of New Orleans to other parts of the country.
The National Centre for Missing and Exploited Children, at the government's request, announced a hotline and website dedicated to reuniting family members separated by the storm.
There also were warnings of new dangers. Health and Human Services Secretary Michael Leavitt said he had received a report from Biloxi, Mississippi, of dysentery - a painful, sometimes-fatal intestinal disease that causes dehydration.
With hot weather, mosquitoes and standing water holding human waste, corpses and other contaminants, diseases such as West Nile virus, hepatitis A, salmonella and E coli bacteria infections were also a concern, he said on CNN.
"We have the ingredients for a bad situation there," Leavitt said.
Hundreds of federal health officers and nearly 100 tonnes of medical supplies and antibiotics were being delivered to the Gulf Coast to try to head off the problem.
Toll in thousands
Local officials had predicted the toll would reach into the thousands, and federal officials agreed on Sunday.
"I think it's evident it's in the thousands," Leavitt said.
Besides Rice, Chertoff and Leavitt, Defence Secretary Donald Rumsfeld and Joint Chiefs of Staff Chairman General Richard Myers travelled to the region on Sunday.
"It's going to take many, many, many months and into years for this area to recover," said Rumsfeld, who took a helicopter tour of New Orleans, met military personnel conducting search-and-rescue missions and visited a concourse where evacuated patients were being treated.
Survivors scramble for food in
Rice, the administration's highest-ranking black official, became its chief defender against charges that help, particularly to the disproportionately black and poor victims in New Orleans, came too slowly.
"Americans don't want to see Americans suffer," she said in Alabama.
On television, Chertoff was omnipresent, dispatched by the administration to appear on all five Sunday news shows after Federal Emergency Management Agency Director Michael Brown's damage-control efforts met with little success last week.
Chertoff echoed the White House line - saying the time to place blame will come later, but he also said federal officials had trouble getting information from local officials on what was going on.
For instance, he said, they had not been told by Thursday of the violence and horrible conditions at the New Orleans convention centre.
But Senator Mary Landrieu, a Democrat from Louisiana, lashed out at federal officials whom she said had denigrated local efforts to deal with the catastrophe.
"If one person criticises them or says one more thing, including the president of the United States, he will hear from me," she said on the ABC's This Week.
"One more word about it after this show airs and I might likely have to punch him. Literally."
And New Orleans Mayor Ray Nagin told NBC News that the situation has been "a tragedy, a disgrace".