Spencer Ackerman February 26, 2007, 9:51 AM

Starting next week, the Senate wades into the muck at the Walter Reed Army Medical Center. The Senate Armed Services Committee announced today that next Tuesday, March 6, a host of responsible Defense officials will parade to the Dirksen building to try to explain how conditions at the Army’s elite hospital complex deteriorated to the horrific conditions depicted in last week’s depressing Washington Post series.

Perhaps the most anticipated testimony will come from the Army’s surgeon general, Lt. General Kevin C. Kiley. The Pentagon reacted to the Post investigation with near-unanimous horror and regret — Army Vice Chief of Staff General Richard Cody took personal responsibility in a Thursday press conference — and vowed to get to the heart of the problem. Kiley has been the exception. While he hasn’t challenged the facts that the paper reported, last week he attacked the expose as “one-sided” and assured reporters, “this is not a horrific, catastrophic failure at Walter Reed.”

Defense Secretary Gates disagrees. On Friday, he declined to endorse Kiley’s characterization, saying “I have not seen anything or heard anything in the time since (the stories ran) to lead me to believe that those articles were in any substantial way wrong.” To get out in front of the scandal, Gates announced the creation of an internal investigation — led by Clinton and Reagan defense officials — into Walter Reed, the Bethesda Naval hospital and “any other centers they choose to examine.” While he said he hadn’t heard of any additional problems with veterans’ outpatient services beyond Walter Reed, Gates emphasized that the Pentagon needs to understand “the scope of the problem.”

The next move will be the Senate’s. Kiley and Cody are called as witnesses, as is Walter Reed’s commanding general, Maj. General George Weightman, and the assistant secretary of defense for health affairs, William Winkenwerder. In addition to next week’s hearing, more Hill action is likely: Winkenwerder is stepping down from his position for what we’re told are unrelated reasons. His nominated replacement, cardiologist and Army Reserve Col. S. Ward. Casscells — who recently returned from Iraq himself — is sure to face a grilling on veterans’ outpatient care as well.