While historically the United States has had close relations with Venezuela, a major oil supplier, friction in bilateral relations rose under the leftist populist government of President Hugo Chavez (1999-2013), who died in March 2013 after battling cancer for almost two years. After Chavez's death, Venezuela held presidential elections in April 2013 in which acting President Nicolas Maduro, who had been serving as Chavez's vice president, defeated opposition candidate Henrique Capriles by a margin of just 1.49%, with the opposition alleging significant irregularities. Venezuela's December 2013 municipal elections demonstrated mixed results for the ruling United Socialist Party of Venezuela (PSUV) and the opposition Democratic Unity Roundtable (MUD). In 2014, the Maduro government has been facing significant challenges, including deteriorating economic conditions (with high inflation and shortages of consumer goods) and high rates of crime and violence. Most significantly, in February, student-led street protests erupted into violence with protestors attacked by Venezuelan security forces and militant pro-government civilian groups. While the protests had largely dissipated by June, at least 42 people were killed on both sides of the conflict, more than 800 injured, and more than 3,000 arrested (while most have been released, some 77 are still being held). A major opposition figure, Leopoldo Lopez, was arrested and imprisoned along with two opposition mayors. Diplomatic efforts to deal with the crisis at the Organization of American States were frustrated in March. The Union of South America Nations (UNASUR) initiated a government/opposition dialogue in April, but the talks broke down in May because of a lack of progress."