The force dubbed "Billary" - the combination of former US President Bill Clinton and his wife - hit Iowa in earnest Tuesday, focusing on lifting Hillary Clinton's candidacy in an early voting state that one aide has described as her weakest. The Clintons were campaigning across the state for three days. The two tried to win over more than 300 Iowa caucusgoers Tuesday morning at a private breakfast on the state fairgrounds. The two arrived Monday night for a rally there, making it the first time they had appeared together in one of the early nominating states that are the focus of the 2008 race since she entered it. Bill Clinton said he is backing his wife because she is the most qualified, not because of any spousal obligation.