** FILE ** Democratic Presidential hopeful, and Senate Foreign Relations Committee member, Sen. Barack Obama, D-Ill., listens as Gen. David Petraeus and U.S. Ambassador to Iraq Ryan Crocker testify on Capitol Hill in Washington about the future course of the war in Iraq in this Sept. 11, 2007 file photo. When Petraeus delivers his assessment of the Iraq war April 8, the next commander in chief will weigh in as well. Republican Sen. John McCain will get a chance to argue that last year's U.S. troop buildup has been a success and withdrawal would be a mistake. Democratic Sens. Hillary Rodham Clinton and Obama will have an opportunity to ask why the United States is still fighting more than five years after the invasion. (AP Photo/Susan Walsh, File)