Buenos Aires  - Venezuelans are set to go to the polls again Sunday, but this time at least one thing is different: precedent shows that President Hugo Chavez can actually lose an election, and accept defeat too.

"If we lose, we lose," Chavez said bluntly in an interview with CNN earlier this month.

Venezuelans are set to vote on a constitutional amendment that would allow the unlimited re-election of the president. The proposal was already part of a broader constitutional reform that was rejected at the polls in December 2007.

Chavez has stressed that he expects to win, but just in case he would not rule out the possibility of calling his countrymen to a further referendum if his proposal again fails. On Wednesday he further said he would accept the result and urged his supporters against violence in case of a disappointment at the polls.

Close to 17 million voters are set to decide Sunday whether Chavez can stand for a further mandate in 2012 at the end of his second term, which could potentially extend his period in power from 1999 to 2019.

Earlier this month, the left-wing populist Chavez, 54, celebrated the 10th anniversary of his rise to power. But his star seems to have lost at least some of its glow, and he looks more vulnerable than he has in the past.

After a landslide election victory in 1999, Chavez - who led a failed military coup in 1992 - has ridden a wave of huge popularity, particularly among Venezuela's poor. He quickly passed a new constitution and was inaugurated for the first of two terms possible under the new rules in 2001.

Chavez later survived a coup that actually ousted him from power for a few hours in 2002, as well as an economically devastating two- month oil strike in 2002-2003 that forced the oil-rich country to import petrol.

He also faced up to a recall referendum in 2004, which he overwhelmingly won.

In 2007, he was inaugurated for his second presidential term, and unless the constitution is changed again he will be required to leave power in 2013 under the current rules.

In late 2007, before an opposition that had gradually set aside its differences to put forward a simply anti-Chavez formula, Chavez failed in a first attempt to change the presidential term limits, when his proposal was narrowly defeated in a referendum.

His supporters insist things have changed.

"I think the current situation is different. The demand for reform required more debate and now there is greater consciousness of the need to go and vote. That is why we have great chances (of success)," said Blanca Eekhout, a spokeswoman for the "yes" camp in the referendum.

"This is a very precise proposal, there is no doubt at the grassroots level and the opposition's lie that we seek a dictatorship has been dismantled," she stressed.

In a highly-polarized country, hundreds of thousands of people opposing the reform marched through the streets of Caracas the week before the referendum, under the motto "No Means No."

"We have neither the resources nor the logistics that the government has. But we have the will, it is the future of the homeland that is at stake," said former opposition presidential candidate Manuel Rosales.

As in 2007, students have played a key role in opposition to the reform proposal.

Moreover, the long-standing opposition to Chavez has been joined by a sector of people who once backed him.

"There are many people who, like me, have voted for President Chavez many times, but now they are going to vote for the Constitution (as it stands)," said Ismael Garcia, leader of the previously pro-Chavez group PODEMOS.

In late 2007, Chavez appeared to come of age politically - in the face of an opposition who had previously denounced his "dictatorial" ways - by accepting his first defeat at the polls since rising to power.

"We respect the rules of the game," Chavez said at the time.

For once, the opposition had to believe him. And indeed, the heterogenous anti-Chavez camp, whose political record was also not impeccable, showed a striking maturity in triumph.

On Sunday, Venezuelans for and against the country's charismatic and controversial president will get another chance to show their relative electoral weights, as well as their political maturity in accepting the results of the vote. (dpa)