BAGHDAD -- Gen. David Petraeus has an enviable problem as he ponders his next report to Congress about the U.S. mission in Iraq. His military surge has been so successful in reducing violence that some officials -- at the Pentagon and the State Department, not to mention in the Democratic Congress -- are wondering whether Petraeus can accelerate his timetable for withdrawal of U.S. troops.The Dems'd love that! Would they take credit?