es and second-guessing that if she heard any more criticism of local efforts, even from the president, she might "punch" him.

The New Orleans mayor, C. Ray Nagin, said matters were improving but remained a "disgrace."

The president of a local Louisiana parish, Aaron Broussard, broke down sobbing on the NBC program "Meet the Press" today as he talked about an elderly woman who drowned while awaiting repeatedly promised help.

"Nobody's coming to get us," Mr. Broussard said, his head sagging. "The secretary has promised. Everybody's promised. They've had press conferences. I'm sick of the press conferences. For God's sake, shut up and send us somebody."

Mr. Bush, criticized even by some supporters for failing to respond more decisively, has ordered additional active-duty troops to the region, and sent top cabinet members there to help guide still-unfinished rescue work.

He dropped his own plans for Labor Day on Monday, saying he would return to Louisiana and Mississippi, and overhauled his month's schedule, canceling a long-anticipated visit by President Hu Jintao of China.

White House advisers scrambled to confront a confluence of critical challenges - including the hurricane, sagging support for the Iraq war and record-high gasoline prices - that politicians say could severely challenge his second-term legislative plans.

The politics of an already-charged season appeared suddenly overshadowed by the depths of the hurricane disaster.

Even the scripts of Sept. 11 commemorations next Sunday may have to be rewritten, as one of the most fundamental lessons Americans thought their leaders had learned - that mountains needed to be moved to prepare for the unexpected - seemed to some to have fallen short.

The secretary of health and human services, Michael Leavitt, said Sunday that Katrina's death toll almost surely was in the thousands.

Michael Chertoff, the homeland security secretary, warned that already-shocked Americans needed to brace for worse as waters recede, baring the full extent of death and destruction.

Meanwhile, Mr. Chertoff said, work was continuing at an almost unimaginable scale, "basically moving the city of New Orleans to other parts of the country." But he added, "I think we are in control of what's going on in the city."

The first major opinion poll since the disaster showed ambivalent feelings toward Mr. Bush's handling of it, far less positive than the near-universal support he received in the days after the Sept. 11, 2001, terror attacks. An ABC poll found that 46 percent of Americans approved of Bush's handling of the crisis, almost exactly half his 91 percent approval rating after Sept. 11, 2001.

Bush sent several top advisers to the region, including Mr. Chertoff, Defense Secretary Donald H. Rumsfeld and Secretary of State Condoleezza Rice, as federal and state authorities reportedly wrestled behind the scenes over which had ultimate authority in the crisis area.

Mr. Chertoff's department has been harshly criticized for the federal failure to prepare adequately for a possible disaster that some emergency officials, and The Times Picayune of New Orleans, had anticipated with eerie precision years ago.

A proposal to detach the Federal Emergency Management Administration from Homeland Security is to be introduced this week in Congress. Some critics say that the Homeland Security takeover of FEMA added a harmful layer of bureaucracy.

Others have questioned the FEMA leadership of Michael Brown, whose background in law, finance and public service includes no prior emergency-management experience.

Mr. Chertoff in turn seemed to cast some blame elsewhere. He said earlier that "our constitutional system really places the primary authority in each state with the governor."

Today, Senator Landrieu, a Democrat whose father, Moon Landrieu, was once the mayor of New Orleans, dropped her earlier reserve about criticizing federal failings.

Mr. Bush had said that the enormousness of the crisis had "strained state and local capabilities."

Local authorities took this as a deeply unjustified criticism, and a distraught Ms. Landrieu said that if she heard any more criticism from federal officials, particularly about the evacuation of New Orleans, she might lose control.

"If one person criticizes them or says one more thing - including the president of the United States - he will hear from me," she said on the ABC program "This Week." "One more word about it after this show airs and I might likely have to punch him. Literally."

She also referred angrily to comments Mr. Bush had made Friday at the New Orleans airport about the fun he had had there in his younger days.

"Our infrastructure is devastated, lives have been shattered," Ms. Landrieu said during a helicopter tour of the area with an ABC interviewer. "Would the president please stop taking photo-ops?"

Mr. Chertoff warned that Americans, already horrified by scenes of misery and chaos in New Orleans, should brace for worse.

"I think we need to prepare the country for what's coming," he told Fox News. As waters recede, "we're going to uncover people who died, maybe hiding in houses, you know, got caught by the flood, people whose remains are going to be found in the streets," he said.

"It's going to be about as ugly a scene as I think you can imagine. Certainly as ugly of a scene as we've seen in this country, with the possible exception of 9/11."

The New Orleans mayor, Nagin, who last week lashed out at federal authorities in an expletive-laced outburst, told reporters on Saturday that while he regretted his language, he was still frustrated by the federal response. "We're still fighting over authority," he said. "A bunch of people are the boss. The state and the federal government are doing a two-step dance."

He added, "I think it's getting better, but the pace is still not sufficient."

In Washington, even some Republicans have warned that the much-assailed White House response could undermine Bush's authority and his legislative agenda, including plans to overhaul the tax code, Social Security and immigration law.

Newt Gingrich, the former House speaker, said that Mr. Bush's handling of the crisis could, if it is seen to improve, re-energize his plans. Otherwise, "it swamps the rest of his agenda."

But the government message has found itself struggling for time on the airwaves against angry criticisms like Ms. Landrieu's, and anguished cries for help, like that of Mr. Broussard, the local official who broke down sobbing on NBC.

"The guy who runs this building I'm in, emergency management, he's responsible for everything," Mr. Broussard said. "His mother was trapped in St. Bernard nursing home and every day she called him and said, 'Are you coming, son? Is somebody coming?' And he said, 'Yeah, Mama, somebody's coming to get you. Somebody's coming to get you on Tuesday. Somebody's coming to get you on Wednesday. Somebody's coming to get you on Thursday. Somebody's coming to get you on Friday.' And she drowned Friday night.

"Nobody's coming to get us," he said through his tears. "Nobody's coming to get us."

Ms. Landrieu warned of the risk to nearly submerged railways lines that serve a wide area of the country. Another hurricane, she said, would have calamitous effect.

"We are one storm away from disaster," she said, looking forward. "Doesn't anybody hear us?"

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