President Bush concludes his address to the nation Thursday night

President Bush is calling for massive federal spending to help rebuild the homes and lives of those affected by Hurricane Katrina. With the president's public approval ratings at record lows, Mr. Bush addressed the nation Thursday evening from the hardest-hit city of New Orleans.

President Bush said the federal government will pay most of the costs of recovering from Hurricane Katrina:  from roads and bridges, to housing and health care, to job training and primary education for hundreds of thousands of people displaced by the killer storm.

"To all who carry a burden of loss, I extend the deepest sympathy of our country. To every person who has served and sacrificed in this emergency, I offer the gratitude of our country," said the president. "And tonight I also offer this pledge of the American people: 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."

The president gave no cost estimate for the huge federal spending, but some analysts predict it will ultimately be greater than the $300 billion Washington has already spent on wars in Afghanistan and Iraq. So far, Congress has approved $62 billion for Hurricane Katrina, but that is expected to run out next month.

Public opinion polls show plenty of blame to go around for the slow pace of the response to the disaster, which has claimed more than 700 lives. Some polls show Americans believe local and state officials are more responsible than the federal government because they failed to have adequate evacuation plans.

But the president too has seen his ratings fall, with more than half of Americans surveyed in a New York Times / CBS News Poll now disapproving of his overall performance. Six in ten say Mr. Bush does not share their priorities.

President Bush, left, is briefed by Chevron Refinery Manager Roland Kell with Mississippi Governor Haley Barbour, right

The president says he wants to know what went wrong in responding to the storm. In a time of continuing terrorist threats, Mr. Bush says detailed emergency planning is a national security priority. "Four years after the frightening experience of September 11th, Americans have every right to expect a more effective response in a time of emergency," said the president. "When the federal government fails to meet such an obligation, I as president am responsible for the problem, and for the solution."

Mr. Bush says the federal government will learn the lessons of Katrina, reviewing every action and making necessary changes so Americans will be better prepared for any challenge be it terrorism or natural disaster.

Before Mr. Bush spoke, Democratic House leader Nancy Pelosi criticized the president's waiving federal wage and environmental rules in affected areas, saying the already devastated Gulf Coast region should not be treated as a laboratory for political opportunism.

Ms. Pelosi says she will not name Democrats to a Congressional investigation into what went wrong, because she does not believe that inquiry will be impartial as it will be led by the president's Republican Party, which holds a majority in both houses of Congress. "The American people deserve to know the truth about how their government prepared for and responded to this crisis," said Representative Pelosi. "That is why Democrats continue to call for a 9/11-type independent investigation into the government's response. The Bush Administration and the Republican Congress should not investigate themselves, and partisanship has no place in this inquiry."

Some of the criticism surrounding the response to the storm has focused on the race and class breakdown of those hardest hit. Most of the people trapped by the floodwaters of New Orleans were black. Opinion polls show an overwhelming majority of black Americans believe help would have come quicker if those stranded were white.

President Bush addressed that issue head-on Thursday, saying that while the Gulf region has some of America's most historic places, it also has deep, persistent poverty. "That poverty has roots in a history of racial discrimination, which cut off generations from the opportunity of America," said the president. "We have a duty to confront this poverty with bold action. So let us restore all that we have cherished from yesterday, and let us rise above the legacy of inequality."

To help those affected, President Bush is calling for a so-called opportunity zone in the areas of Louisiana, Mississippi, and Alabama hit by the storm. Within this zone, Mr. Bush says there would be immediate incentives for job-creating investment and tax relief and loan guarantees for small businesses.He wants $5,000 worker recovery accounts to help people find new jobs or pay for child care while they are looking.