It was supposed to be a close vote; some even believed that an upset was in the works. But when the dust settled, Venezuelan President Hugo Chavez had won another election. This time, however, his margin of victory was considerably reduced, from 25 percentage points six years ago to about 10 percentage points on Sunday. Despite Mr. Chavez's vow to complete the "Bolivarian revolution" he launched in 1998, he must take into account the views of the many Venezuelans who voted against him. That assumes the president will complete his six-year term — an open question given his health problems.

Mr. Chavez was a retired lieutenant colonel, best known for launching a failed coup in 1992, when he won the presidency 14 years ago. He was then, and remains, a fiery populist who has promised a socialist revolution for his country in the name of the Latin American nationalist Simon Bolivar. During his tenure in office, he has transformed Venezuelan society, using class warfare — he refers to the rich and middle class as "the squalid ones" — to bolster his support: He has nationalized private property and businesses, while providing free medical care, housing, education and food to the country's poor.

Essential to his success is the flood of oil revenues Venezuela enjoys as a member of OPEC, the global petroleum cartel. With proven reserves putting the country in the ranks of the top 10 oil producers, oil revenues account for about 94 percent of Venezuela's export earnings, more than half of federal budget revenues, and around 30 percent of gross domestic product. Fonden, the country's state investment fund, accounts for nearly a third of all investment in Venezuela and half of public investment; in 2011, it received 25 percent of government revenue from the oil industry. Over the last seven years, it has absorbed about $100 billion of Venezuela's oil revenue — much of it used to buy support for Mr. Chavez.