WASHINGTON (Reuters) - Three days before the first presidential debate, allies of Barack Obama and Mitt Romney debated on Sunday how the encounter between the White House contenders will influence the U.S. election. In typical straight-talking fashion, New Jersey Governor Chris Christie predicted fellow Republican Romney's performance at Wednesday's debate would alter the course of the campaign, weeks before the November 6 vote. "This whole race is going to turn upside down come Thursday morning," Christie told CBS' "Face the Nation. ...