The failure to respond more quickly to Hurricane Katrina resulted in unnecessary “suffering” by Gulf Coast victims and exposed a weakness in the government’s ability to respond to a national crisis, two Senators investigating the much-criticized relief effort said Tuesday.

The Senate Homeland Security and Governmental Affairs Committee will hold a closed-door briefing today to begin examining the federal, state and local government’s actions in the hours and days following the hurricane that destroyed New Orleans and other communities across three states.

“In its initial response to the catastrophe of Hurricane Katrina, particularly in Louisiana, governments at all levels failed in this obligation,” said Sen. Susan Collins (R-Maine), who will oversee the Senate inquiry. “The result was enormous suffering, needless deprivation and widespread destruction.”

Formal hearings on the matter are expected to begin next week. New Orleans Mayor Ray Nagin, Louisiana Gov. Kathleen Blanco and Michael Brown, who oversees the Federal Emergency Management Agency, will all likely be asked to testify, said Sen. Joe Lieberman (D-Conn.), the ranking member on the Homeland Security Committee.

“You can’t do a thorough investigation of what happened without calling state and local officials and that goes to the top,” Lieberman said.

The Connecticut Democrat even left open the possibility that the committee might ask President Bush to offer insight into the matter, but noted it would not be in the form of testimony. Rather, Lieberman said, it would be “an informal conversation.”

“As always, it will only happen with the consent where the president has a personal feeling that he has something to tell us, that he wants to tell the Senate. So we will see.”

At about the same time Collins and Lieberman were outlining their inquiry Tuesday, Bush announced his administration would launch an “investigation to find out what went right and what went wrong.”

It is not known how many people died in what is being described as the nation’s most horrific natural disaster, but early estimates suggest the number of dead could be in the thousands. Critics suggested many of the deaths in New Orleans could have been avoided, had a comprehensive emergency plan been activated.

For several days now, federal officials and Louisiana authorities have been assigning blame to each other for the slow relief response that left people helpless and homeless without any aid for several days. In the first full day back following the month-long Congressional recess, Senators began to take sides on the issue.

Senate Minority Whip Dick Durbin (D-Ill.) called on Brown to step down from his post, charging that the FEMA head has “very thin credentials.”

“I think it is time to put somebody in charge who knows how to handle a disaster and recovery,” Durbin said.

But Bush allies suggested the federal government has shouldered an unnecessary amount of blame at the slow relief response and said it is Louisiana’s elected officials who need to be held accountable.

“I have been a little disappointed in Louisiana, in it seems like there is not the single strength of leadership there,” said Sen. Jeff Sessions (R-Ala.). “Our governor, [Bob] Riley (R-Ala.), was on top of the thing from the beginning. And he was telling FEMA and the president and everybody what we needed. And we pretty much got what we needed.”

Already, there appears to be disagreement over whether FEMA should be removed from the Department of Homeland Security and elevated to a Cabinet-level agency. As of now, Collins and Lieberman said they favored keeping FEMA under the Homeland Security Department’s command.

But Senate Minority Leader Harry Reid (D-Nev.) said he prefers that FEMA become a separate independent agency.

“FEMA has become a toothless tiger,” Reid said. “It has been stripped of its ability to respond. It should be re-established as a Cabinet-level position.”

In addition to assessing what went wrong with the relief effort in New Orleans, the Homeland Security panel will also analyze how the nation’s emergency response system failed.

“It immediately occurred to me that if our system did such a poor job when there was no enemy, how would the federal, state and local governments have coped with a terrorist attack that provided no advance warning and that was intent on causing as much death and destruction as possible,” Collins said. “How is it possible that almost four years to the day after the attacks on our country, with billions of dollars spent to improve our preparedness, that a major area of our nation was so ill-prepared to respond to a catastrophe?”

Collins and Lieberman pledged the Senate inquiry would not interfere with the ongoing relief effort.

Many Senators such as Sen. Chuck Hagel (R-Neb.) said they welcomed this approach because the first priority needs to be helping the victims. But Hagel echoed the sentiment of many of his colleagues by stating that a full accounting would eventually need to take place.

“There needs to be some accountability,” Hagel said.