Senator Clinton said yesterday that “we have failed as a nation” in responding to Hurricane Katrina nearly a year after the storm flooded New Orleans and devastated a wide swath of the Gulf Coast.

Speaking at a Katrina memorial at the Riverside Church in Harlem, Mrs. Clinton faulted the federal government for not responding to the victims of the hurricane as it did to the victims of the terrorist attacks of September 11, 2001.

“We know as people of faith we have a continuing obligation to those in need,” Mrs. Clinton told an audience of hundreds. “But so does our government. So do those who are entrusted with the public well-being.

“And a year later, we have to say we have failed as a nation,” she said. “Our leadership has turned its back on those people who need us still.”

Clinton also renewed her call for an independent, bipartisan panel modeled on the National Commission on Terrorist Attacks Upon the United States to investigate the government response to Katrina. The Senate, in a party-line vote last fall, rejected a Clinton bill that would have established a Katrina commission.

Both houses of Congress have made their own inquiries, and a White House panel led by President Bush’s domestic security adviser, Frances Townsend, issued a 228-page report in February titled, “Lessons Learned.” But Mrs. Clinton said those investigations lacked “vigor and accountability.”

She championed the efforts of the Samuel DeWitt Proctor Conference, a nonprofit organized by African-American ministers that has launched its own commission to investigate the response to Katrina.

With Tropical Storm Ernesto battering Haiti yesterday and headed in the direction of the Gulf Coast, Mrs. Clinton said that she hoped the government would be ready and that the levees in New Orleans would hold.

“We won’t know until it happens,” she told reporters after the service. She added: “They say they’re better prepared than they were. I hope to good that they are, because I don’t think those people should have to suffer again.”

In his weekly radio address on Saturday, Mr. Bush said Katrina had “revealed that federal, state, and local governments were unprepared to respond to such an extraordinary disaster.” Repeating a pledge to “learn the lessons of Katrina,” the president said that in Mississippi and Louisiana, “we can see many encouraging signs of recovery and renewal, and many reminders that hard work still lies ahead.” He is set to visit the region this week.

Mrs. Clinton spoke yesterday at one of several Katrina memorial services held at churches around the country. Outside the Riverside Church near 120th Street, about a dozen protesters rallied against Mrs. Clinton’s position on the Iraq war, but inside, she was greeted warmly, and her remarks received a standing ovation.

Also attending the service was her anti-war challenger for the Democratic Senate nomination, Jonathan Tasini. Mr. Tasini sat three rows behind Mrs. Clinton, but the two did not acknowledge each other.

“We were not looking for a Suozzi moment,” Mr. Tasini joked to reporters afterward, referring to the Nassau county executive, Thomas Suozzi, who staged a surprise meeting with the man he is challenging for the Democratic gubernatorial nomination, Eliot Spitzer, at a Mineola train station in June.

Mr. Tasini said “there is no daylight between me and Senator Clinton” on Katrina. Turning to his critique of the Iraq war, Mr. Tasini said the billions spent on the conflict could be redirected to the recovery efforts along the Gulf Coast.