Venezuelans voted Sunday in local elections seen as a popularity test for leftist President Hugo Chavez, a year after the anti-US leader lost a referendum on extending his authority.

Chavez supporters set off military wake-up calls and music in some districts, with polls open at around 6:00 am (1030 GMT).

First estimates suggested abstention in the vote for governors and mayors would be around 50 percent, with some 17 million eligible to vote. Polls were due to close at 4:00 pm (2030 GMT).

Surveys suggest Chavez's United Socialist Party of Venezuela (PSUV) will likely hold most states and cities, but may lose some posts as voters express concern over escalating corruption, inefficiency and crime.

Chavez, in power for almost 10 years, has crossed the country campaigning for his party's candidates, ensuring that the polls will also test support for him and his socialist revolution.

"My destiny is at stake ... Whether Chavez keeps governing Venezuela will depend on what happens on November 23," the president said recently.

Diverse opposition groups have agreed to join together to increase chances for victory and run single candidates in a majority of 22 gubernatorial races and 328 mayoral races.

The opposition currently controls two states -- northwestern Zulia and northeastern Nueva Esparta -- and another five are in the hands of Chavez dissidents.

Surveys suggest the opposition could win between five and seven governorships in their bid to gain back some lost power.

Opposition gains in symbolic areas of the oil-rich OPEC country such as Caracas or big states Chavez's allies have controlled for years would be the biggest blows.

Chavez, a friend to Iran, Russia and Cuba's Fidel Castro, is highly aware of his need for a visible victory to push forward his cause.

The 54-year-old led a failed military coup in 1992 and was briefly overthrown for two days in April, 2002.

But until last year's narrow referendum loss, the outspoken anti-liberal -- popular among the country's majority poor who he has helped with oil-funded social programs -- had always emerged from polls with convincing victories.

Many residents of the vast Petare slum, which clings to the capital's hills, arrived early to vote Sunday.

Maria Teresa Padron, 80, voted for a candidate from Chavez's party to show her support for the president.

"God sent us Chavez. No one will give us the well-being this president offers us. No one took us into account before, but thanks to him, I live well now," Padron said.

Another voter, Cesar Alberto, chose an opposition candidate for a municipal post to protest the current mayor.

"The president came to support his candidates but not to see the problems here. There's rubbish, violence and a lack of water," he said, pointing to piles of trash.

Famous for his fiery language, Chavez has threatened to imprison opponents, or even send tanks onto the streets if his party loses in the populous northwestern state of Carabobo.

Some 140,000 soldiers were policing the polls.

Around 300 candidates, mainly from the opposition, have been prevented from running in the elections.

Many say that, despite last year's referendum defeat, Chavez still seeks to change the constitution in a bid to stay in office beyond 2013 when his second six-year term will end.