No question looms larger on the national scene than how Americans will react to the progress reported by Iraq commander Gen. David Petraeus and U.S. Ambassador Ryan Crocker when they testify before Congress next week. A look at the course of opinions about the Iraq conflict over the past few years suggests that two crucial but opposing factors in American thinking will likely shape the public’s response. The first is the growing perception that the war is a failing enterprise. The second is the public’s continuing awareness of the risks associated with a hasty retreat.