WASHINGTON, Sept 7: President George W. Bush and his Republican Party launched a major effort on Wednesday to limit the political damage from the botched federal response to Hurricane Katrina.

President Bush is asking Congress for as much as $50 billion in immediate aid for dealing with the catastrophe but the White House indicated that more money would be needed eventually.

Republican chairmen of various Senate committees pledged to investigate the recovery effort -– and later why the initial response was ineffectual.

Also on Wednesday, Democrats demanded that President Bush sack Michael Brown, the head of the Federal Emergency Management Agency that has been widely vilified for its reaction to the hurricane and the deadly aftermath.

Rep. Mark Foley, a Florida Republican, also backed the demand, saying that Mr Brown’s agency had flaws in responding to the hurricanes in Florida last year as well.

Other Republican leaders said they have received the message that there is frustration over the federal response.

“Have I got an earful? You bet I have,” said Sen. Norm Coleman, Minnesota Republican, who said he heard about it from voters at Minnesota’s state fair this weekend.

While willing to support the demand for an investigation, Republicans are still blaming the Democrat-led state and city administrations in Louisiana for the failure of the relief and rescue efforts in the state.

But Mr Bush, Defense Secretary Donald H. Rumsfeld and top congressional Republicans acknowledged that the federal response fell short because, in Mr Coleman’s words, “the federal officials didn’t do a good enough job of filling that void fast enough”.

The senator from Minnesota said that the federal government must now turn its immediate failure into an opportunity to show it is in control.

But the opposition Democrats said that the federal response was still not adequate. The top Democrat in the Senate said the final cost could be $150 billion -– instead of the $50 billion Mr Bush is seeking.

“Through my conversations with officials on the ground and in consultation with Senator Mary Landrieu of Louisiana, I believe that the recovery and relief operations will cost up to and could exceed $150 billion,” said Senate Minority Leader Harry Reid, Nevada Democrat.

At the Pentagon, Mr Rumsfeld ordered a mandatory ‘lessons learned’ on what the armed forces had done right and wrong in the week-old disaster that has likely to have killed thousands in Louisiana, Mississippi and Alabama.

He added that the military’s involvement will not affect the US effort in Iraq.

“We have the forces, the capabilities and the intention to fully prosecute the global war on terror while responding to this unprecedented humanitarian crisis here at home,” Mr Rumsfeld said.

Meanwhile, there was disagreement among Republicans over how quickly to proceed on the investigations.

The Republicans who run the House and Senate oversight committees said they will begin next week, but Sen.

Trent Lott, a Mississippi Republican whose home was destroyed by the storm, asked them not to distract from the relief effort. House Speaker J. Dennis Hastert also backed this advice.