Mitt Romney said Friday he will not make an 11th-hour presidential run to try to stop Donald Trump from winning the Republican nomination, the day after sharply attacking the real estate mogul's candidacy. "I won't run for president," Romney told host Matt Lauer on NBC's "Today" show. Lauer asked the 2012 GOP presidential nominee three times about his 2016 ambitions, pressing for an "unambiguous" response after Romney appeared to leave the door to a bid slightly open.