On a national day of prayer for the victims of Hurricane Katrina, a bipartisan group of federal lawmakers toured the damaged region as New Orleans prepared to let the first people back into the city.

Leading the nation in the National Day of Prayer and Remembrance, President Bush said the rebuilding of the devastated Gulf Coast will "measure our unity as a people."

"Our nation remains in the shadow of a storm that departed two weeks ago. We are humbled ... and feel small beside its power," Bush said in remarks Friday at Washington’s National Cathedral. "We mourn with those who mourn and we ask for strength in the work ahead."

Meanwhile, a bipartisan group of senators on Friday led by Senate Majority Leader Bill Frist and Senate Minority Leader Harry Reid toured areas hard-hit by Katrina, including New Orleans. Among the lawmakers on the trip were Louisiana Sens. David Vitter, a Republican, and Mary Landrieu, a Democrat.

"It reminded me of air flights I have taken over battle zones," Sen. Joseph Lieberman, D-Conn., told FOX News about flying over the area and seeing the devastation.

'Lonely Pain of People'

Bush was speaking on the day he dedicated as a national day of prayer and remembrance for the victims of Hurricane Katrina (search). Bush, the first lady and other national leaders attended the non-denominational service led by spiritual leaders from around the country.

Portions of the service were delivered by faith leaders from: New Orleans, La.; Biloxi, Miss.; Mobile, Ala.; Houston and Dallas.

"The destruction is immense,” Bush said. "Yet the hurt always comes down to one life, one family. ... The lonely pain of people whose earthly possessions were swept away and the uncertainly of men and women and children driven away from the lives they knew."

He added: "Our nation joins with them to pray for comfort and sorrow, for the reunion of separated families, and a holy rest for the ones who died."

Bush thanked those who have answered the "cries of neighbors," providing food, water and shelter, but reminded the audience that there was much work ahead.

"The destruction of this hurricane was beyond any human power to control, but the restoration of broken communities and disrupted lives now rests in our hands, and we accept this responsibility not as a burden or chore but as an opportunity to serve our fellow Americans as they would do for us," Bush said.

Bush also repeated a message first delivered Thursday night to the nation from New Orleans — that reconstruction should be used to erase racial and economic inequality.

"As we clear away the debris of a hurricane, let us also clear away the legacy of inequality," the president said. "One day, Americans will look back at the response to Hurricane Katrina and say that our country grew not only in prosperity, but in character and justice."

Bush Pledges Plenty of Federal Support

Bush pledged Thursday to "do what it takes" to help the Gulf Coast region recover from the hurricane — a step he says should include national economic, social and military changes.

"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," Bush said in a prime-time, 23-minute address.

On Friday, Bush said he would rely on cuts to government spending but not tax hikes to pay for the multi-billion-dollar recovery plan.

In nearly all of Mississippi, electric power has been restored; deliveries have begun at the Port of New Orleans; all major gasoline pipelines are operating; levees have been repaired; and water is being pumped out of the city faster than expected.

Emergency managers also are working to get drinking-water and waste-water treatment systems operating and are preparing bodies for burial. The death toll from Katrina reached 794 on Thursday, with 558 of them found in Louisiana.

Congress has provided more than $60 billion in federal aid that has been used in part to help more than 500,000 evacuee families get emergency food, clothing and other essentials. The government's goal is to get people out of shelters by the middle of October, Bush said.

"This is an unprecedented response to an unprecedented crisis, which demonstrates the compassion and resolve of our nation," he said.

Support has already come from several federal agencies, including the Coast Guard, the Federal Emergency Management Agency (search), the United States military, the National Guard and the Department of Homeland Security.

The Department of Health and Human Services has sent 1,500 health professionals and 50 tons of medical supplies; the Department of Labor is helping displaced people apply for temporary jobs and unemployment benefits; and the U.S. Postal Service is registering new addresses so people can get their mail. Many residents of the area had already received their Social Security checks.

Not Just Action, But Reflection

Though on his fourth trip to the region since Katrina hit, Bush has been roundly criticized for what many say is a slow federal response to the storm. The president again took blame for the government's delayed reaction.

"Four years after the frightening experience of Sept. 11, 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," he said.

Bush has ordered every Cabinet secretary to review of the government response to the hurricane and come up with lessons to be learned. DHS and its local counterparts are undertaking an immediate review of emergency plans in every major city in America.

"In a time of terror threats and weapons of mass destruction, the danger to our citizens reaches much wider than a fault line or a flood plain. I consider detailed emergency planning to be a national security priority," he said.

On Thursday, House Speaker Dennis Hastert named Virginia Rep. Tom Davis, chairman of the House Government Reform Committee, to lead the panel to investigate the slow turnaround from the federal government.

Democratic argue that an independent commission is better suited for a review since a congressional committee will cover up the president's failings.

House Minority Leader Nancy Pelosi of California and Senate Minority Leader Harry Reid of Nevada said the president must do more than offer comforting words.

"It takes more than just taking responsibility to right the many wrongs that occurred over the past two weeks. The American people need answers from independent experts outside of the political arena to learn from the past and prepare and protect our nation and our communities for the future. We can and must do better," they said in a written statement.

Bush also announced that a "team of inspectors general" will monitor spending as federal dollars are doled out.

Earlier Thursday, DHS named a special inspector general to handle hurricane relief.

The perception of a sluggish response to the storm has led to the lowest approval ratings of Bush's presidency. A FOX News-Opinion Dynamics poll released Thursday showed the president's approval rating at 41 percent, down from 45 percent last month. Bush's disapproval rating reached 51 percent this month.

The Associated Press contributed to this report.