Enrique Pena Nieto, (C) presidential candidate of the Institutional Revolutionary Party (PRI) and his wife Angelica Rivera pose with their children from previous marriages after voting in Atlacomulco July 1, 2012. Mexicans began voting for a new president on Sunday with the opposition party that dominated the country for most of the past century poised for a comeback after the ruling conservatives failed to provide strong growth or halt a brutal drugs war. REUTERS/Tomas Bravo (MEXICO - Tags: POLITICS ELECTIONS)