Sen. Hillary Rodham Clinton on Thursday called on Defense Secretary Donald H. Rumsfeld to resign, hours after excoriating him at a public hearing over what she called "failed policy" in Iraq. "I just don't understand why we can't get new leadership that would give us a fighting chance to turn the situation around before it's too late," the New York Democrat and potential 2008 presidential contender said in an interview with The Associated Press. "I think the president should choose to accept Secretary Rumsfeld's resignation." "The secretary has lost credibility with the Congress and with the people," she said. "It's...