A referendum by President Hugo Chavez to change Venezuela's constitution went to the vote Sunday amid deep opposition to his ambitions to impose a socialist economy and rule for life. The predicted closeness of the result raised the prospect of post-poll violence among supporters and opponents.
Chavez, a 53-year-old former paratrooper who is using his country's vast oil wealth to mount a leftist challenge to US influence in Latin America, has warned of a suspected CIA plot to stir up trouble over his reform.
He has vowed to cut oil supplies to the United States if unrest occurs.
"There will be no oil for anyone, and the price per barrel will go up to 200 dollars," he said Saturday.
On Friday, in his final campaign rally, the ally to Iran and Cuba said: "A vote 'yes' is a vote for Chavez - a vote 'no' is a vote for (US President) George W. Bush."
Surveys released in the lead-up to the referendum showed the result too close to call, with many in Chavez's traditional powerbase - the poor who make up 80 percent of the 27-million-strong population - balking at the constitutional changes.
Measures Chavez is trying to usher in include allowing limitless re-election for the president, giving the government the right to gag the press in emergencies, and permitting the expropriation of property.
He is also seeking to cut the workweek from 40 hours to 36 and reinforce costly social programs improving literacy and health among the poor. The president, who first came to power in 1999, has said he wants to remain in charge "until 2050," when he would be 95.