CARACAS (Reuters/BBC) -- Voters have been turning out in numbers in Venezuela’s referendum on far-reaching constitutional changes sought by President Hugo Chavez.

Venezuelans voted Sunday on whether to allow Chavez to stay in power for as long as he keeps winning elections or hand him his first defeat at the polls.
Chavez, who has easily won one election after another against a fragmented opposition, is in the hardest campaign of his life as he moves to deepen his revolution by reforming the constitution.
He predicts he will win by 10 percentage points but most polls show a neck-and-neck race between backers of the referendum that Chavez says will usher in “21st century socialism,” and those who are against it.
The former paratrooper, who has led Venezuela since 1999 and is a close ally of Cuba and Iran, also has escalated his verbal attacks on the U.S. government.
“Whoever votes ‘Yes’ is voting for Chavez and whoever votes ‘No’ is voting for George W. Bush, president of the United States,” Chavez told supporters at a massive rally in Caracas on Friday.
A “Yes” vote would scrap limits on how long Chavez can rule as president and he has said he will stay on for decades if Venezuelans keep voting for him.
The reforms also would give him control over the central bank and foreign currency reserves bloated by high oil export revenues, reduce the workday to six hours and extend social security benefits to informal workers like street vendors.
Chavez, 53, leads a growing anti-U.S. bloc in South America.
Chavez says the Bush administration of planning to meddle with the referendum vote and has threatened to halt oil exports to the United States. Citing a confidential memo, the Venezuelan government is claiming the CIA is fomenting unrest to challenge the referendum.