WASHINGTON — Senators on Tuesday said they would consider every avenue to fix a badly broken system of caring for troops wounded in battle, as Bush administration officials apologized anew for cases of neglect at Walter Reed Army Medical Center.

"The war in Iraq has divided our nation but the cause of supporting our troops unites us," said Sen. Carl Levin, D-Mich., who chairs the Armed Services Committee. "We will do everything we can possibly do — not as Democrats or Republicans — but as grateful Americans — to care for those who have served our nation with such honor and distinction."

As his panel questioned top defense officials, Levin also used the revelations of bad conditions and outpatient care at Walter Reed to take a swipe at President Bush's war polices.

"Today's hearing is about another example of the lack of planning for a war that was premised on the assumption that combat operations would be swift, casualties would be minimal, and that we would be welcomed as liberators, instead of being attacked by the people we liberated," he said.

Levin's panel convened the second congressional hearing in two days regarding the poor conditions at Walter Reed. Reports of wounded troops battling excessive red tape and dilapidated living conditions have enraged Republicans and Democrats, who say they are worried that problems at Walter Reed point to a broader problem of neglect across the nation at military hospitals.

Meanwhile, President Bush said Tuesday he has named former Sen. Bob Dole and former Secretary of Health and Human Services Donna Shalala to lead a White House investigation.

"We have a moral obligation to provide the best possible care and treatment to the men and women who served our country," Bush said in a speech to the American Legion. "They deserve it and they're going to get it."

At Tuesday's Senate hearing, David Chu, the personnel chief at the Pentagon, also promised action.

"I'm deeply chagrined by the events that bring us to this hearing this morning," Chu said.

Sen. John McCain, R-Ariz., said Congress in coming weeks will consider whether legislation or additional resources are needed.

"I am dismayed this ever occurred," said McCain, top Republican on the Senate Armed Services Committee, who was captured and wounded during the Vietnam War. "It was a failure in the most basic tenets of command responsibility to take care of our troops."

During a hearing Monday, two soldiers wounded in combat and a spouse of a wounded soldier recounted nightmarish stories of frustration as they tried to get medical attention and disability compensation.