Veteran leftist Andrés Manuel López Obrador took office as Mexican president on Saturday, vowing to see off a “rapacious” elite in a country struggling with corruption, chronic poverty and gang violence on the doorstep of the United States. Backed by a gigantic Mexican flag, the 65-year-old took the oath of office in the lower house of Congress, pledging to bring about a “radical” rebirth of Mexico to overturn what he called a disastrous legacy of decades of “neo-liberal” governments. “The government will no longer be a committee at the service of a rapacious minority,” said the new president, who is...