Caracas (AFP) - Shrugging aside his country's economic ruin and growing international isolation, Venezuela's socialist President Nicolas Maduro seeks a second six-year term in controversial elections Sunday that are being boycotted by the opposition.

The US moved to further isolate his government on Friday, just two days before the polls, by slapping sanctions on Maduro's powerful deputy and socialist party leader Diosdado Cabello.

"We are imposing costs on figures like Diosdado Cabello who exploit their official positions to engage in narcotics trafficking, money laundering, embezzlement of state funds, and other corrupt activities," said US Treasury Secretary Steven Mnuchin.

It was a fresh blow to Maduro, whose ebullient campaign meetings have done little to disguise a lack of enthusiasm in the oil-rich but cash-poor South American country, where the result is widely seen as a foregone conclusion.

He held his final rally on Bolivar Avenue in downtown Caracas on Thursday, enlisting former Argentine soccer star Diego Maradona to fire-up the crowd.

Applauded by Maduro and his supporters, Maradona declared himself a Maduro "soldier," waved a Venezuelan flag and punched the air as he danced to loud reggaeton music on the stage.

"Trust me, if you give me your vote and give us victory, I swear I will lead great economic changes and drive an economic revolution that will shake the world," pledged Maduro.

The 55-year-old former bus driver wore a green shirt with the image of his late predecessor, Hugo Chavez, emblazoned on the sleeve.

Maduro is the clear favorite, despite trailing in opinion polls to his main rival Henri Falcon, and a low approval rating among Venezuelans fed up with hyperinflation, food and medicine shortages, rising crime and broken water, power and transportation networks.

"I'm not going to vote for anyone. I'm concerned with surviving every day and things are getting more and more screwed up," fruit seller Alexis Rodriguez, 40, told AFP.

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Opinion polls show Falcon leading with 30 percent of voter intentions, compared to Maduro's 20 percent. An evangelical candidate, Javier Bertucci, has 14 percent.

However, "low enthusiasm will likely reduce voter turnout and enable Maduro to control the outcome without major social backlash," said analyst Risa Grais-Targow of Eurasia Group.

- Divided opposition -

Maduro, with a tight grip on the electoral and military authorities, faces a bitterly divided opposition.

Falcon wore the yellow, blue and red of Venezuela's flag at his final rally in his western stronghold of Barquisimeto.

He told his supporters he had "faith" in overcoming the boycott, and "that we are going to vote massively, as our country needs."

But he has failed to secure the endorsement of the main opposition leaders, who remain committed to boycotting the vote, and was unable to convince Bertucci to drop out of the race and unify what opposition voters there are.

"People have lost faith in protest and the vote, that's why there's apathy. The Venezuelan is bewildered and desperate," said analyst Juan Manuel Raffalli.

The Democratic Unity Roundtable (MUD) opposition coalition, increasingly pinning its hopes for change on outside pressure forcing the socialists to remove Maduro, have won support from the US, EU and 14 countries of the Lima Group who have called for the vote to be postponed.

Canada this week banned Venezuelan expatriates from voting in the election.

The powers accuse Maduro of undermining democracy, usurping the power of the opposition-dominated parliament by replacing it with his all-powerful Constituent Assembly, and cracking down on the opposition. Protests in 2017, still fresh in the collective memory, left around 125 dead.

The MUD's most popular leaders have been sidelined or detained, the boycott their only remaining weapon.

They accuse Maduro of luring supporters to vote on Sunday with rewards of food boxes.

- Increasing isolation -

Maduro, meanwhile, continues his defiance in the face of increasing international isolation and US and EU sanctions.

"We will not give in to blackmail," he says. "We do not care if they do not recognize us. The president of Venezuela is elected by the people, not Donald Trump."

The latest sanctions, leveled at Maduro's right-hand man Cabello, a former speaker of the National Assembly, also targeted his wife and brother.

But despite Maduro's rhetoric and the world's largest oil reserves, the country faces ruin, with the IMF citing a drop of 45.0 percent in GDP since Maduro took over in 2013. The crippled oil industry lacks investment and its assets are increasingly prey to debt settlements as the country defaults.

And worse, the US threatens an oil embargo on top of sanctions that have hit Venezuela's efforts to renegotiate its debt.

"The most likely scenario is greater international isolation and economic deterioration," said Diego Moya-Ocampos of IHS Markit analysts.

"The key factors will be the economy and the army," said analyst Michael Shifter. "The country is a powder keg and something could provoke unrest that would be difficult to contain."