By RICARDO CASTILLO     In 2012, Enrique Peña Nieto won the presidential election representing the Institutional Revolutionary Party (PRI), defeating Democratic Revolutionary Party (PRD) candidate Andrés Manuel López Obrador (AMLO) by a narrow, but credible, margin of 38 to 32 percent of the general vote count. Unlike in the aftermath of the 2006 election when AMLO lost to National Action Party