CARACAS, Venezuela - Venezuela was on edge last night as voters awaited the outcome of a much-anticipated referendum that would give President Hugo Chavez sweeping new constitutional powers.

Hours after the polls closed yesterday, the government still had not released official results, causing political leaders to speculate that the vote was too close to call.

That would be a stunning development in a country where Chavez and his supporters control nearly all the levers of power.

"The result will be quarrelsome," Vice President Jorge Rodriguez said in comments broadcast on national television.

Both supporters and critics of Chavez pointed to exit polls in their favor, suggesting a contentious outcome to the vote.

Electoral officials said official results could be released early today, after reports from polling stations around the country trickled in here.

In the weeks leading up to the vote, members of previously splintered opposition movements joined disillusioned Chavez supporters in an attempt to defeat the proposals, which would abolish term limits, allow Chavez to declare states of emergency for unlimited periods and increase the state's role in the economy, among other measures.

A defeat of the proposed constitutional overhaul would temporarily suspend Chavez's Socialist-inspired transformation of Venezuela, once a staunch ally of the United States that has become a leading nemesis of the Bush administration's policies in the developing world.

Under Chavez, Venezuela has taken the most profound leftward turn of any Latin American nation in decades.

The streets here were unusually free of traffic last night.

Supporters of Chavez gathered around the presidential palace downtown to await the results, as they have done in past elections.

The occasional blast of fireworks from hillside slums broke the rare silence of this city.

Unlike past elections here, this time the government did not invite observers from the Organization of American States or the European Union, opening itself to potential claims of fraud.

The voting appeared to unfold largely without irregularities, though there were isolated reports of fraud and violence in parts of the country.

The referendum followed several weeks of street protests and frenetic campaigning over the 69 amendments to the Constitution proposed by Chavez and his supporters.

It caps a year of bold moves by the president.

He forged a single Socialist party among his followers, forced a television network critical of the government off the public airwaves, and nationalized oil, telephone and electricity companies.

The United States remains the largest buyer of Venezuela's oil, despite deteriorating political ties.

But this long commercial relationship is starting to change as Chavez increases exports of oil to China and other countries while gradually selling off the oil refineries owned by Venezuela's government in the United States. *