Rescuers scoured New Orleans' swamped houses and shattered high-rises Thursday, finding many holdouts finally ready to flee the filthy water and the stench of death — in what might be the last peaceful sweep before forced evacuations begin.

"Some are finally saying, 'I've had enough,'" said U.S. Immigration and Customs Enforcement (search) spokesman Michael Keegan. "They're getting dehydrated. They are running out of food. There are human remains in different houses. The smells mess with your psyche."

Meanwhile, Congress quickly approved 97-0 an additional $51.8 billion for relief and recovery from Hurricane Katrina late Thursday.

In Washington, President Bush pledged the government would "cut through the red tape" to provide an immediate $2,000 in disaster assistance to families displaced by Katrina and make sure they continue receiving Medicaid, food stamps, jobless compensation, and other federal benefits.

He designated Sept. 16 as a national day of prayer and remembrance for victims across the Gulf Coast.

"We have much more work to do," the president said. "But the people that have been hurt by this storm know that — need to know that the government is going to be with you for the long haul."

Across a flooded New Orleans where as many as 10,000 holdouts were believed to be stubbornly staying put, police made it clear in orders barked from front porches and through closed doors that they would return — next time, with force.

Police said they were 80 percent done with their scan of the city for voluntary evacuees, after which they planned to begin carrying out Mayor Ray Nagin's (search) order to forcibly remove remaining residents from a city filled with disease-carrying water, broken gas lines and rotting corpses.

"The ones who wanted to leave, I would say most of them are out," said Detective Sgt. James Imbrogglio. "There may be a few left, so we're going to go check one of our last areas that's underwater today and then hopefully that will be it."

The job of carrying out the mayor's order was left largely to the 1,000 or so remaining members of New Orleans' beleaguered police force.

'We Are Going to Be Sensitive'

"We are not going to be rough," said Police Chief Eddie Compass. "We are going to be sensitive. We are going to use the minimum amount of force."

The near-conclusion of the voluntary evacuation came as receding floodwaters revealed still more rotting corpses. Nagin has said the death toll in New Orleans alone could reach 10,000, and state officials were ordering 25,000 body bags.

Volunteer rescuer Gregg Silverman, part of a 14-boat contingent from Columbus, Ohio, said he expected to find many more survivors in his excursion through the city's flooded streets. Instead, he found mostly bodies.

"They had me climb up on a roof, and I did bring an ax up to where a guy had tried to stick a pipe up through a vent," Silverman said. "Unfortunately, he had probably just recently perished. His dog was still there, barking. The dog wouldn't come. We had to leave the dog just up there in the attic."

As for other bodies his group encountered: "Obviously we are not recovering them. We are just tying them up to banisters, leaving them on the roof."

At St. Rita's nursing home in the town of Chalmette, authorities struggled to identify as many as 30 residents who may have perished.

Dr. Bryan Patucci, coroner of St. Bernard Parish, said the nursing home staff apparently believed it was more dangerous to move the residents than keep them at the building. He said it may be impossible to identify all the victims until authorities compile a final list of missing persons.

Contaminated water throughout the city began to raise serious fears of disease.

"There is no question there's a concern there but we're working very closely with the EPA [Environmental Protection Agency] to do everything we can to mitigate that," Brig. Gen. Bruce Berwick, a principal engineer staff officer for the U.S. Army Corps of Engineers in Mississippi, told FOX News on Thursday.

The Corps said the city was still about 60 percent flooded — down from as much as 80 percent last week — but was slowly being drained by 37 of the 174 pumps in the Orleans, St. Bernard and Plaquemines parishes, and 17 portable pumps. They can pump out 11,000 cubic feet per second, roughly equal to 432 Olympic-size swimming pools per hour.

"Throughout the region, there's terrific work being done," Berwick of the Corps told FOX News, adding that his workers are helping to clear debris and install roofs, as well as providing food and other commodities and removing water from New Orleans.

"I'm happy to say, through heroic efforts, they've been able to close the breach in the 17th Street canal" in New Orleans, and 23 of the city's 48 pumps are working, Berwick added. "We will continue that effort and try to accelerate the removal of water as time goes on."

Engineers said the mammoth undertaking could take months, and could be complicated by corpses getting clogged in the pumps.

"It's got a huge focus of our attention right now," said John Rickey of the Corps. "Those remains are people's loved ones."

Cheney Tours Gulf Coast; Aid Package Pushed

Bush dispatched Vice President Dick Cheney to the region Thursday amid persistent criticism of the sluggish pace of the federal response. Stopping along a street of splintered homes in Gulfport, Miss., Cheney said much progress is being made in a relief effort he termed "very impressive."

"I think the progress we're making is significant," Cheney said. "I think the performance, in general, at least in terms of the information I've received from locals, is definitely very impressive."

He added: "That's not to say there's not an awful lot of work to be done — there is."

Cheney told reporters he was struck by the "very positive, can-do" attitude of Mississippians toward the help they are getting. In general, Mississippi officials have been much more complimentary of the federal hurricane response than those from Louisiana and, particularly, New Orleans.

While Cheney spoke, a passer-by hurled an expletive at the vice president. "First time I've heard it," Cheney said, when asked if he was hearing a lot of such sentiments.

Later in New Orleans, Cheney visited a repaired levee and surveyed the damage as he rode through the streets in an armored Humvee.

"They want to know how to rebuild, and that's certainly the vice president's job here today," Cheney's wife, Lynne, told FOX News after the press conference in Gulfport.

"Their spirits are great and, you know, we're here to try to help them," she said. "Let's take this huge problem that's been visited upon us and let's fix it."

At Louis Armstrong Airport, now a bustling military encampment, New Orleans' City Council met for the first time since Katrina, with members defending how they handled the disaster and defiantly vowing to rebuild.

"New Orleans has been built back from many disasters," said Councilwoman Cynthia Hedge Morrell. "New Orleans was here before there was a United States of America."

Some 400,000 homes in the city are without power, with no immediate prospect of getting it back. Where water has been restored, it is not drinkable. The city is still dangerous — not primarily, as it was last week, from armed criminals, but from the sewage-laden floodwaters, which are believed to contain E. coli and other dangerous germs.

Fires were also a continuing problem. At least 11 blazes burned across the city Thursday, including a rash of fires that raged across the campus of historically black Dillard University, detstroying three large buildings.

Across town at the Audubon Zoo, curator Dan Maloney said some of the 1,400 animals were lost, but keepers have been too busy caring for survivors to take a count. The dead included two sea otters that were moved to different tanks before Katrina and died from stress.

Some of the most vulnerable creatures — including several macaws, eagles and a pair of African lions — were being transferred to other zoos.

Said chief gardener Tran Asproditis: "It's just sad that this has happened and it is going to take us a long time to recover and reopen for the kids. And that's what we want to do, is just open so the kids can come back."

The Associated Press contributed to this report.