US 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 soldiers at Walter Reed Army Medical Center in Washington. The surprise move came one day after Harvey fired the two-star general in charge of the medical center in response to disclosures of problems at the hospital compound. 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 Harvey, after firing Maj. Gen. George Weightman as the head of Walter Reed, chose to name as Weightman's temporary replacement another general whose role in the controversy was still in question. 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 world's foremost medical facilities.