Sen. Hillary Rodham Clinton faces a possible new threat to her presidential ambitions. Former Vice President Al Gore has again been entertaining offers to run for president. Gore has been discussing a run for a third party nomination with family and close aides. "Al Gore has been energized by the attention he's been receiving as America's leading environmentalist," a political source close to Gore said. "He believes this might present an opportunity to become president or at least try again." Sources close to Gore said Ralph Nader has sought to recruit the former vice president to run as the candidate...