U.S. Says Closely Watching Venezuela Referendum Steps***CARACAS, Venezuela (Reuters) - The United States, which has clashed with leftist Venezuelan President Hugo Chavez over policies, on Friday strongly backed plans for a national referendum on whether he should stay in office. The United States, like other nations in the hemisphere, backs a constitutional solution to the crisis (in Venezuela)," Stephen McFarland, charge d'affaires at the U.S. Embassy in Caracas, told a news conference. "We are all following very closely the referendum process," he added. ***