President George W Bush has toured central New Orleans to see the wrecked city first hand.
Power is down but conditions are said to be improving in New Orleans
In comments during his visit, he admitted that authorities may have relaxed before the worst effects of Hurricane Katrina became clear.
But he said it was "preposterous" to suggest that war in Iraq left too few troops to cope with the disaster.
His third and longest visit to the scene comes as opinion polls show a deep dissatisfaction with his response.
Polls in Time and Newsweek magazines suggested most Americans were unhappy with the speed with which government reacted to the 29 August disaster.
The Newsweek poll gave Mr Bush his lowest approval rating as president - just 38%.
There have been arguments over whether federal officials or those from local and state government are most to blame for the crisis.
However, with recovery work in full swing and making headway, the president's aides hope criticism of his administration's slow response will start to subside, the BBC's Daniel Lak reports from New Orleans.
Mr Bush spent Sunday night aboard the USS Iwo Jima, a helicopter-carrier moored off New Orleans.
On Monday morning he was briefed aboard the ship by US Coast Guard Vice Admiral Thad Allen, who is commander of the hurricane response operation, in a slideshow update on the latest relief efforts.
He then went on to survey the waterlogged city.
With Adm Allen, New Orleans Mayor Ray Nagin, and Louisiana Governor Kathleen Blanco, he stood on the back of a military truck and was driven through flooded streets, ducking half-collapsed power cables.
He said Congress should examine whether the response to the disaster failed in any way.
"My attitude is that we need to learn everything that we possibly can... There'll be time to take a step back and to take a sober look at what went right and what didn't go right. There's a lot of information floating around that will be analysed in an objective way," he said.
The president admitted that authorities may have relaxed too early, when they thought the worst of Hurricane Katrina had passed, thinking they had "dodged the bullet".
He was also questioned about the feeling among some that people were abandoned without help in the hurricane aftermath because they were black.
He replied: "The storm didn't discriminate and neither will the recovery effort.
"When those coastguard choppers, many of whom were first on the scene were pulling people off roofs they didn't check the colour of a person's skin, they wanted to save lives."
Law and order have returned to thinly-populated New Orleans
After Louisiana, Mr Bush was travelling on to Gulfport in the neighbouring state of Mississippi where the wind and waves of Katrina did the most direct damage.
In New Orleans itself, the airport is set to reopen for commercial flights and work has begun to clear rubbish in the city.
Searchers are now finding more dead bodies than survivors and are confronted with the challenge of identifying the remains of people left in fetid waters or high temperatures.
But breaches in the flood defences have been repaired and pumps appear to be lowering the floodwater in residential areas.
The overall confirmed death toll is still around 400 with officials saying the final number of dead could be much lower than the thousands feared initially.
"We didn't lose as many lives as had been predicted, although we're still in the process of finding those we lost," said Governor Blanco.