WASHINGTON – More than 350,000 families made homeless by Hurricane Katrina would get emergency housing vouchers averaging $600 a month for up to six months under a measure approved Wednesday by the Senate.

Any displaced family regardless of income would be eligible for the program, which is slated to cost $3.5 billion over six months.

The measure, by Sen. Paul Sarbanes, D-Md., was attached on a voice vote to an unrelated spending bill covering the Commerce and Housing and Urban Development departments. The Senate is slated to pass the overall bill Thursday, but a final version needs to be worked out with the House, which passed a similar spending bill for the two departments last June.

Action on the vouchers in the Senate came the same day Republican and Democratic senators alike sharply criticized the federal government for failing to respond more quickly to the disaster.

“At this point, we would have expected a sharp, crisp response to this terrible tragedy,” said Sen. Susan Collins, R-Maine, who chaired a Senate panel Wednesday morning that began investigating what she called a governmentwide sluggish response to one of the worst natural disasters in U.S. history.

“I’m very troubled by the hesitant and halting initial response at all levels of government particularly in Louisiana,” Collins later added in a telephone interview.

“We are still so ill-prepared to cope with a catastrophe. We want to learn from what went wrong,” said the senator, who chairs the Committee on Homeland Security and Governmental Affairs, which oversees the Federal Emergency Management Agency.

Senate Democrats also scolded the nation’s security chief on Wednesday for failing to take advantage of a national emergency response plan and sending massive federal aid to the Gulf Coast before Hurricane Katrina hit.

Democrats said Homeland Security Secretary Michael Chertoff delayed declaring Katrina an “incident of national significance” – a designation that would have triggered a quick and massive federal response – until a day after the hurricane hit, even though weather forecasts predicted the storm would cause widespread destruction.

A Chertoff spokesman denied the charge, pointing to millions of readymade meals, thousands of blankets and dozens of federal rescue teams sent to the region as the hurricane approached.

Despite some of their own criticisms, Senate Republicans scuttled an attempt Wednesday by Sen. Hillary Clinton, D-N.Y., to establish an independent, bipartisan commission – similar to one enacted after the Sept. 11, 2001, terror attacks – to examine what went wrong in Katrina’s wake.

Collins’ committee Wednesday tried to focus more on how to help the victims going forward, but she said her panel would later consider the more difficult questions of what went wrong. “We will ask the hard questions about the adequacy of planning efforts for this long-predicted natural disaster” in future hearings, she said.

“I come here shocked and angry,” said former Mayor of New Orleans Marc Morial in his testimony to Collins’ committee.

Morial, who is also the president and CEO of the National Urban League, encouraged the need for a victims’ compensation fund much like what was offered to victims after Sept. 11. He also supported the idea of a rebuilding czar who would have access to both Congress and the president.

Former California Gov. Pete Wilson said that to hasten the recovery, governmental officials should cut red tape wherever possible by setting aside unnecessary rules imposing delays and waiving waiting periods for unemployment benefits. State organizations also can issue bridge loans to close the gap before federal aid arrives.

Patricia Owens, former mayor of Grand Forks, N.D., a city that flooded in 1997 after an unusually snowy winter left 100 inches to thaw, advised evacuees to take their “pets, pills and pillows,” knowing they would be gone for a long time. The majority of people left her city, and Owens learned two lessons about evacuation: the importance of providing the public with a constant stream of emergency information and the necessity of having strong communication among community, city, town and state institutions.

Joanna Broder of Boston University Washington News Service contributed to this report.