WASHINGTON, (By Sheryl Gay Stolberg, NYTimes) September 9, 2005 - The senior senator from Louisiana returned to the Capitol on Thursday not just as a lawmaker but also, in her words, as "a daughter of the Crescent City."

The senator, Mary L. Landrieu, whose father was a storied mayor of New Orleans, whose brother is Louisiana's lieutenant governor, who walked her children out of her lakeside home expecting, correctly, that she would never see it again, was back in the Senate chamber, full of passion and rage at President Bush and what she called "the staggering incompetence of the national government."

Ms. Landrieu, a Democrat who was nearly put out of office in 2002 after Mr. Bush campaigned intensely for her Republican opponent, had mostly held her fire against the president in the aftermath of Hurricane Katrina. But her tone changed markedly on Thursday, with a 20-minute speech that was at turns poignant and defiant.

"We know the president said, quote, 'I don't think anybody anticipated the breach of the levees,' " Ms. Landrieu said. "Everybody anticipated the breach of the levee, Mr. President, including computer simulations in which this administration participated."

The senator went on to describe how the creator of Mr. Bill, the clay figurine whose cry of "Ohh noooo!" was long a staple of "Saturday Night Live," had used the character in public service announcements to warn southern Louisianians of the dangers they would face in an extraordinary storm.

"How can it be," she asked, "that Mr. Bill was better informed than Mr. Bush?"

As she spoke, Ms. Landrieu was surrounded by about two dozen colleagues on the Senate floor, all of them Democrats except one, Senator Thad Cochran of Mississippi. When she finished, they encircled her, offering hugs as if comforting a widow at a funeral.

Because her family is so steeped in New Orleans politics - her father, Moon Landrieu, was both mayor of New Orleans and then, under President Jimmy Carter, secretary of housing and urban development - the senator, perhaps more than any other Washington official, has become a national spokeswoman for victims of the hurricane. She returned to Washington, where she owns a luxurious brick home a few blocks from the Capitol, late Wednesday night.

Ms. Landrieu predicted that the cost of repairs to the Gulf Coast would top $200 billion, and pledged to find out why the federal response "was so incompetent and insulting to the people of our states."

At one point in her speech, she addressed Mr. Bush directly, saying: "Mr. President, we need you. We need your help." At another, she spoke of a tearful interview she had Sunday with George Stephanopoulos of ABC News.

"I was not crying in anguish because the home that I walked out of with my children was gone - I knew it would be gone when I left," she said. "It was an anguished cry of plea to the only person that I thought could hear, and that was God himself. And I think he has heard, because the people of my state have cried out to him for now over a week and a half. But as he gives us the grace and the wisdom to do our job, I hope we can do it well."