Under the populist rule of President Hugo Chávez, first elected in 1998 and most recently re-elected to a six-year term in December 2006, Venezuela has undergone enormous political changes, with a new constitution and unicameral legislature, and even a new name for the country, the Bolivarian Republic of Venezuela. U.S. officials and human rights organisations have expressed concerns about the deterioration of democratic institutions and threats to freedom of expression under President Chávez, who has survived several attempts to remove him from power. The government has benefited from the rise in world oil prices, which has sparked an economic boom and allowed Chávez to increase expenditures on social programs associated with his populist agenda. Since he was re-elected, Chávez has announced new measures to move the country toward socialism. His May 2007 closure of a popular Venezuelan television station (RCTV) that was critical of the government sparked student-led protests and international condemnation. The Chávez government's proposed constitutional reforms, subject to a referendum scheduled for December 2, 2007, include many amendments that have been controversial, such as the removal of presidential term limits and the government's ability to suspend certain constitutional rights during a state of emergency. The United States traditionally has had close relations with Venezuela, the fourth major supplier of foreign oil to the United States, but there has been friction in relations with the Chávez government. U.S. officials have expressed concerns about President Chávez's military arms purchases, his relations with such countries as Cuba and Iran, his efforts to export his brand of populism to other Latin American countries, and concerns about the state of democracy.