President Bush (search) will tour the hurricane-devastated Gulf Coast region on Friday and has asked his father, former President George H.W. Bush, and former President Clinton to lead a private fund-raising campaign for victims, the White House said Thursday.

White House press secretary Scott McClellan said Bush will survey the Alabama and Mississippi coast by helicopter, then go on to New Orleans. He also will tour some locations on the ground. He got a higher-altitude view Wednesday when Air Force One dropped several thousand feet to fly directly over the region during Bush's flight from his Texas ranch back to Washington.

"The president has wanted to visit the area as soon as possible," McClellan said. "We didn't go sooner because we didn't want to be disruptive of efforts on the ground."

Bush had said earlier Thursday that thousands more victims of Hurricane Katrina (search) still need to be rescued and acknowledged the frustration of people who need food, water and shelter.

"I fully understand people wanting things to have happened yesterday," he said in a live interview in the Roosevelt Room of the White House with ABC's "Good Morning America" program. "I understand the anxiety of people on the ground. ... So there is frustration. But I want people to know there's a lot of help coming."

He said that while the terrorist attacks on Sept. 11, 2001 (search) were a man-made disaster, the aftermath of Sept. 11 and Hurricane Katrina were "just as serious in both cases."

"New Orleans is more devastated than New York was," Bush said.

Bush has directed his staff to try to assess the economic impact of the storm as the administration prepares an emergency budget request for Congress. Bush was hearing his economic advisers' preliminary estimate in the afternoon after a lunch with Federal Reserve Chairman Alan Greenspan.

"The hurricane does have some national impact," McClellan said.

Bush asked his father and Clinton to lead the fund-raising campaign after their successful similar efforts in the wake of the Asian tsunami that hit last December. He made the request of them Wednesday and the three planned a Thursday afternoon meeting in the Oval Office.

McClellan said that Bush trusted the view of administration officials that the response effort so far is "going well."

But, he added, "The people on the ground who needed help yesterday, he certainly understands their frustration."

Bush urged a crackdown on looting and crime that has spread throughout New Orleans.

"I think there ought to be zero tolerance of people breaking the law during an emergency such as this — whether it be looting, or price gouging (search) at the gasoline pump, or taking advantage of charitable giving or insurance fraud," Bush said on ABC. "And I've made that clear to our attorney general. The citizens ought to be working together."

Bush, who spoke as tens of thousands of people were evacuated on buses from the Superdome in New Orleans (search) to the Astrodome in Houston, more than 300 miles away, expressed sympathy for those still stranded.

"Thousands have been rescued, there are thousands more to be rescued," he said.

"I just can't imagine waving a sign that says `Come and get me now.'"

Bush brushed off criticism that he did not return to Washington from his monthlong stay at his Texas ranch on Tuesday, in the immediate aftermath of the hurricane. Upon returning Wednesday, he held a meeting with top government officials guiding hurricane relief and made remarks in the Rose Garden.

"I hope people don't ... play politics during this period of time," he said. "This is a natural disaster — the likes of which our country may have never seen before — and it's a national emergency. And what we need to do as a nation is come together to solve the problem and not play politics. There'll be ample time for politics."

Homeland Security Secretary Michael Chertoff, (search) meanwhile, said one problem is that "we have an ongoing flood situation even as we're in the middle of recovering from the hurricane."

"We've got hundreds of thousands of people who have been displaced," Chertoff said in an interview on NBC"s "Today" show. "This is unprecedented in this country's history and it's going to call for the kind of relief effort which we've been able to mount overseas, and we're now going to have to mount at home."

An additional 10,000 National Guard (search) troops from across the country began pouring into the Gulf Coast on Wednesday to shore up security, rescue and relief operations. The new units brought the number of troops dedicated to the effort to more than 28,000, in what may be the largest military response to a natural disaster.

The Pentagon was sending a broad contingent of ships, aircraft, trucks, medical support and other personnel to support federal agencies already providing aid to gulf region, including 60 helicopters to be used for search and rescue operations, damage assessment flights and the distribution of supplies.

With key Gulf Coast refineries and pipelines out of service, the Energy Department tried to keep fuel production steady by tapping an emergency government stockpile of oil and to temporarily ease pollution standards on gasoline and diesel fuel. But the president raised the possibility that the hurricane will lead to even higher gasoline prices and shortages in some areas.

Besides agreeing to release oil from the Strategic Petroleum Reserve (search), Bush said the administration has waved some Environmental Protection Agency regulations on blended fuel, which will mean there will be more fuel available, not only domestically, but also from imports.