Manuel Balce Ceneta, AP Photo President Bush speaks to the media during a news conference in the White House today with Iraqi President Jalal Talabani. Click photo for larger image.

WASHINGTON -- For the first time, President Bush today said that Hurricane Katrina exposed "serious problems" in disaster response at all levels of government and vowed that he will take responsibility for federal lapses in aiding the victims.

At the same time his new acting director of the Federal Energy Management Agency, R. David Paulison, promised to "get those people out of the shelters, and we're going to move and get them the help they need."

The federal government is already at work building thousands of houses in Louisiana but many think several hundred thousand homes will be needed. Paulison, who spoke to the president by phone last night, said Bush promised he would have the full support of the federal government in getting shelter for those who lost everything in the storm.

At a press conference with Iraqi president Jalal Talabani in the East Room of the White House, Bush said, "to the extent the federal government didn't fully do its job right, I take responsibility."

The White House said that Bush will make his forth trip to the hurricane ravaged Gulf Coast on Thursday and will make an address to the nation that night.

Today he was asked if Americans should be worried whether the government could handle a major terrorist attack because of the problems it had dealing with the aftermath of Katrina.

"Are we capable of dealing with a severe attack? That's a very important question and it's in the national interest that we find out what went on so we can better respond," the president said before leaving for New York to attend the annual meeting of the U.N. General Assembly.

While touring the devastation yesterday, Bush accepted the resignation of FEMA director Michael Brown, who was widely criticized for ineptly leading the federal response to the hurricane and the flooding of New Orleans.

Bush immediately replaced Brown with Paulison, who is also U.S. fire administrator and has been director of emergency preparedness for FEMA. Paulison has more than 30 years as an emergency responder.

Brown's resignation two weeks after the hurricane hit was not unexpected. Homeland Security Secretary Michael Chertoff signaled administration unhappiness with his performance Friday, when the secretary publicly removed him from overseeing Katrina disaster relief efforts. Brown had been heavily criticized for acting too slowly to rescue thousands of people trapped in New Orleans.

The announcement of Brown's resignation came while Bush was touring hurricane ravaged areas of Mississippi and Louisiana.

In a statement, Brown said he had become a distraction and that his leaving was in the "best interest" of the president and FEMA. "There is no other government agency that reaches people in a more direct way," he said. "It has been the best job in the world to help Americans in their darkest hours."

Brown, who got the FEMA job in 2001, came under fire for his lack of hands-on experience in disaster relief and for overstating his credentials on his resume. That led a chorus of Democrats to call for his ouster last week.

Bush at first had indicated, with Brown at his side, that he was satisfied with the director's performance, saying publicly, "Brownie, you're doing a heck of a job."

But inside the administration, few believed that. Although TV reports had been showing thousands of poor and black Americans stranded in New Orleans without food, water or medical attention, Brown told reporters that he did not know about the 20,000 evacuees at the convention center in New Orleans until 24 hours later.

Chertoff grew alarmed and told Bush that he was not satisfied with the way FEMA was performing. Bush sent Vice President Dick Cheney to the region, who confirmed that criticism of FEMA and of Brown was mounting.

Bush then told Chertoff to do what he had to do, and Chertoff named Thad Allen, a Coast Guard vice admiral, to head up the federal response to Katrina.

In a statement last night, Chertoff said Brown had managed 160 disasters during his tenure at FEMA and that he was "a good man" who did everything he could to coordinate the disaster response to Katrina.

Sen. Trent Lott, R-Miss., whose home was demolished in the hurricane, said everyone was overwhelmed by the scope of the disaster. Nonetheless, he said, Brown was acting more like a private than a general, and that FEMA's on-scene leadership had improved since Allen took over. Senate Majority Leader Bill Frist, R-Tenn., also said he was impressed with the way Allen had stepped into the job and immediately had taken charge without ruffling feathers at the local and state levels.

Democrats who for days had been calling for Brown's ouster grumbled that Bush should have fired him, rather than letting him resign. House Minority Leader Nancy Pelosi, R-Calif., said Brown's departure was long overdue.

The bipartisan leaders of the Senate Homeland Security and Government Affairs Committee, which oversees FEMA, agreed that Brown's competence had become a distraction from the relief and recovery effort.

The committee chairman, Sen. Susan Collins, R-Me., said she hoped that Brown's stepping down would end the "continuing barrage" of questions about his credentials, his leadership ability and decisions that he made in preparation for and response to Katrina and would now refocus attention on the relief and recovery.

The labor union that represents FEMA workers, the American Federation of Government Employees, said Brown's resignation was appropriate but inadequate. Union President John Gage said Brown's departure "does nothing to restore the slashed funding for disaster mitigation that FEMA has suffered. It does not undo the damage done by the connected contractors who were used to push aside career FEMA employees, only to provide unusable studies and materials."

Criticism has mounted over poor communications; over buses that took days to arrive to transport people out of peril; over squabbling between state, local and federal authorities; over cuts in FEMA's budget; and over the lack of security, food, water and medical care. As of last night, the hurricane and flooding had claimed 426 lives and displaced about a million people.

Partly as a result, Bush's job-approval rating has sunk below 40 percent in various polls, the worst showing so far in his presidency.

Yesterday, Bush told hurricane victims that "recovery is on the way" and that progress is being made, although "a lot of serious and hard work" has yet to be done. He said relations among various levels of government have improved and that people "are beginning to think about ... the long-term revival of New Orleans" and surrounding parishes.

He strenuously denied allegations that relief was delayed because so many victims were poor and black. "The storm didn't discriminate, and neither will the recovery effort," he said.

Bush said he knew that there has been a lot of "second-guessing" and that there will be time for learning lessons and finding out what went wrong. But he complained that there has been too much of a "blame game" occurring, and he rejected it.

"My attitude is that we need to learn everything we possibly can. We need to make sure that this country is knitted up as well as it can be in order to deal with significant problems and disasters," he said. "Meantime, we got to keep moving forward."

If Bush decides to nominate Paulison as permanent head of FEMA, he will need to be confirmed by the Senate, although he was confirmed previously to head the U.S. Fire Administration, which is now part of FEMA. Such hearings are certain to be fiery recriminations of what went wrong with relief efforts in the immediate aftermath of Katrina.

Chertoff said in a statement last night that he expected to make additional appointments to the FEMA team, "including a permanent deputy director to augment the resources available to assist with FEMA's vital mission." A number of top FEMA officials are political appointees with little or no disaster relief experience.

Today, the president travels to New York to meet with various world leaders before making a speech at the United Nations tomorrow. Asked by reporters if he were ready to switch from the demands of hurricane recovery to refocus on foreign policy, he replied, "I can do more than one thing at one time."

He added that he hoped by the time his presidential term ends that Americans would realize that the government and individuals in it can do more than one thing at one time. He has a hurricane recovery briefing every morning, he said. "If I'm focusing on the hurricane, I've got the capacity to focus on foreign policy and vice versa."