While historically the United States has had close relations with Venezuela, a major oil supplier, friction in bilateral relations rose over the past decade under the leftist populist government of President Hugo Chávez, who died in March 2013 after battling cancer for almost two years. First elected in 1998, Chávez had won reelection to another six-year term in October 2012, capturing about 55% of the vote compared to 44% for opposition candidate Henrique Capriles. After Chávez's death, Venezuela held presidential elections in April 2013 in which acting President Nicolás Maduro, who had been serving as Chávez's vice president, defeated Capriles by a margin of just 1.49%. In both of those presidential elections, the incumbent candidate benefited from the use of state resources and media for his campaign, and the opposition alleged significant irregularities in the 2013 election. 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).