WASHINGTON — Army Secretary Francis J. Harvey abruptly stepped down Friday as the Bush administration struggled to cope with the fallout from a scandal over substandard conditions for wounded Iraq soldiers at Walter Reed Army Medical Center.

Harvey's sudden departure was the most dramatic move yet in an escalating removal of commanders with responsibilities over one of the military's highest-profile and busiest medical facilities.

Hours earlier, President Bush ordered a comprehensive review of conditions at the nation's network of military and veteran hospitals in the wake of the Walter Reed disclosures.

Defense Secretary Robert Gates said Harvey had resigned, but senior defense officials speaking on condition of anonymity said Gates had asked Harvey to leave. Gates was displeased that the officer Harvey had chosen as interim commander of Walter Reed — Lt. Gen. Kevin Kiley, a former commander of Walter Reed — has been accused by critics of long knowing about the problems there and not improving outpatient care.

"I am disappointed that some in the Army have not adequately appreciated the seriousness of the situation pertaining to outpatient care at Walter Reed," Gates said in the Pentagon briefing room. He took no questions from reporters.

On Thursday, Harvey fired the medical center's previous commander, Maj. Gen. George Weightman, for failures linked to the outpatient treatment controversy. Many had speculated that Weightman would be relieved of command, but Harvey's departure was a major surprise.

The Army announced Friday that Maj. Gen. Eric R. Schoomaker will be the new commander of Walter Reed.

"From what I have learned, the problems at Walter Reed appear to be problems of leadership," Gates said. "The Walter Reed doctors, nurses and other staff are among the best and most caring in the world. They deserve our continued deepest thanks and strongest support."

The revelations about shoddy facilities and wounded soldiers enduring long waits for treatment have embarrassed the Army and the Bush administration at a time when the White House is scrambling to shore up eroding support for the Iraq war. It has prompted numerous calls in Congress for more information, and sullied the reputation of what is supposed to be one of the military's foremost medical facilities.

The defense secretary indicated he was unhappy with the way Army leaders had responded to the Walter Reed disclosures.