President Bush has promised to rebuild New Orleans and the Gulf Coast as he attempts to rebound from the political fallout of hurricane Katrina.
In a prime-time address from the French Quarter in New Orleans, Mr Bush said the scale of the disaster means a massive reconstruction project is required, "one of the largest reconstruction projects the world has ever seen".
But he stopped short of offering a financial commitment that some members of the US Congress say could reach $200 billion, exceeding the cost of the Iraq war. Katrina has killed more than 700 people and displaced a million others.
"Throughout the area hit by the hurricane, we will do what it takes. We will stay as long as it takes to help citizens rebuild their communities and their lives," he said.
"It was not a normal hurricane, and the normal disaster relief system was not equal to it," he said. "The system, at every level of government, was not well coordinated, and was overwhelmed in the first few days.
"Four years after the frightening experience of September 11th, Americans have every right to expect a more effective response in a time of emergency. When the federal government fails to meet such an obligation, I as president am responsible for the problem, and for the solution," Mr Bush said.
It was the president's first major speech on the hurricane, coming two weeks after the storm struck, an address many from the president's Republican Party had hoped he would have delivered much sooner.
But Mr Bush did not endorse calls, mostly from opposition Democrats, for an independent investigation modelled on the commission that investigated intelligence failures in the run up to the September 11, 2001 terrorist strikes.
Mr Bush is suffering record-low public approval ratings and faces a public with less confidence in the government's ability to respond to crises, a major theme of his 2004 re-election campaign.
Two emergency requests for a total of $62.3 billion made by Mr Bush sped through the US Congress. That money is expected to carry the relief effort into October, at which point another request for billions will be required.