Populist or professor? Contrite or uncompromising? President Obama will have a chance Wednesday to reintroduce himself to the nation when he delivers his first official State of the Union address before a joint session of Congress. The prime-time speech, which will be aired on all major TV networks and cable stations, could hardly come at a more critical time for a president grappling with double-digit unemployment, sinking poll numbers and the possible collapse of his top domestic policy priority, an overhaul of the nation's health-care system. "As often as the president has spoken over the past year, critics on the...