Caracas (AFP) - Tensions mounted within hours of presidential polls opening in Venezuela Sunday as the elections chief lashed out at opposition candidate Edmundo Gonzalez Urrutia and incumbent Nicolas Maduro vowed to ensure the outcome is “defended.”

Independent polls suggest the vote poses the biggest challenge yet to 25 years of “Chavismo,” the populist movement founded by Maduro’s socialist predecessor and mentor, Hugo Chavez.

But analysts say the president is unlikely to concede defeat.

Maduro, 61, is seeking a third six-year term at the helm of the once wealthy petro-state where GDP dropped by 80 percent in a decade on his watch, pushing more than seven million of its 30 million citizens to emigrate.

He is accused of locking up critics and harassing the opposition in a climate of rising authoritarianism.

Based on its own numbers, the regime insists it will prevail over Gonzalez Urrutia, a 74-year-old former diplomat reluctantly thrust to the top of the opposition ticket after its leader was disqualified by the state apparatus.

Maduro counts on a loyal electoral machinery, military leadership and state institutions in a system of well-established political patronage.

After casting his ballot Sunday, the president insisted he was the only Venezuelan politician being “persecuted” – by the “world powers, by Goliath.”

And he vowed to “make sure” the results announced by the CNE electoral authority – most of whose member are regime loyalists – are “defended.”

CNE chief Elvis Amoroso, addressing reporters, described the opposition as “enemies of Venezuela,” and said its candidate “rejects the constitution.”

Gonzalez Urrutia, for his part, said the opposition was “prepared to defend” the vote as he called for a high turnout.

“We trust our armed forces to respect the decision of our people,” he added.

- ‘Hope there is democracy’ -

Long queues of voters formed at many ballot stations hours before polls opened for 12 hours at 6:00 am (1000 GMT).

“I have been here since 4:30 in the morning, and I hope it will be a successful day,” lawyer Griselda Barroso, 54, told AFP in Caracas.

“I hope there is democracy.”

US Secretary of State Antony Blinken urged everyone involved to “respect the democratic process.”

“The international community is going to be watching this very closely,” he told reporters in Japan.

The vote is the product of a deal reached last year between the government and opposition with backing of the United States – which temporarily eased sanctions imposed after Maduro’s 2018 reelection was rejected as a sham by most Western and Latin American countries.

The measures were tightened once again after Maduro reneged on conditions – barring the candidacy of wildly popular opposition leader Maria Corina Machado who was replaced on the ballot by little-known Gonzalez Urrutia.

The United States is keen for a return to stability in Venezuela – an ally of Cuba, Russia and China that boasts the world’s largest oil reserves but diminished production capacity.

Economic misery in the South American nation has also been a major source of migration pressure on the US southern border.

Most Venezuelans live on just a few dollars a month, with the health care and education systems in disrepair and biting shortages of electricity and fuel.

The government blames sanctions, but observers point the finger at corruption and government inefficiency.

On Friday, a Venezuelan NGO said Caracas was holding 305 “political prisoners” and had arrested 135 people with links to the opposition campaign since January.

- ‘Bloodbath’ -

Days before the vote, Maduro had warned Venezuela could turn into a “bloodbath” if he loses.

The comments drew condemnation from leaders including Brazil’s Luiz Inacio Lula da Silva, who said: “Maduro has to learn: if you win, you stay. If you lose, you go.”

Concerns were further stoked when Caracas blocked international observers at the last minute, including four Latin American ex-presidents who had their plane held up in Panama on Friday.

Observers from the European Union had their invitation withdrawn weeks ago by authorities that have allowed a small delegation from the US-based Carter Center.

The word “change” is on the lips of many Venezuelans.

“There is a lot of expectation for change, that we can move forward, to have a change in government that will allow those abroad to return,” voter Ali Diaz, a 30-year-old marketer, told AFP in the capital.

About 21 million Venezuelans are registered to vote, but only an estimated 17 million still in the country are eligible.

The government has deployed tens of thousands of security forces and enforced ramped-up border control and a prohibition on public gatherings and protests.