Caracas: Venezuela’s political rivals will carry out more fraught Vatican-backed talks on Saturday as they struggle to stabilise a volatile country stricken by food shortages.

The talks, which began late on Friday, could determine whether the sides maintain their fragile dialogue or the oil-rich South American country returns to antagonism and instability.

“Progress was made on key agreements, the exact contents of which will be revealed” at the end of the meetings, Ernesto Samper, secretary general of the Union of South American Nations (UNASUR) said.

A short time before the meeting got under way, President Nicolas Maduro declared that he had done everything in his power to achieve a resolution with opposition leaders, who for months had been seeking to remove him.

“I have done everything, both possible and impossible, for there to be peace talks with the right — without ultimatums and without bullying,” the socialist leader said.

After four hours of negotiations on Friday, the parties agreed to meet the following morning at 10:00am (1400 GMT) for a second round of talks.

Mass street protests erupted after authorities last month blocked the opposition’s bid to hold a referendum on removing Maduro from office.

The two sides declared a “truce” at a first meeting 11 days ago and agreed to resume talks on Friday. The outlook appears combative.

Opposition MUD coalition leader Jesus Torrealba warned his side would seek early elections if Maduro keeps refusing a referendum, as he has vowed.

“The MUD is seeking an electoral solution to this crisis through the negotiating table,” Torrealba said.

“Venezuela is a pressure cooker. The recall vote was an escape valve, and the government sealed it up.”

The MUD has demanded that its imprisoned members be released.

The opposition launched its efforts to remove the president after winning control of the legislature in January.

Maduro has vowed not to bow to pressure and ultimatums.

He said the government would present a plan for ending the crisis at the meetings and urged the MUD not to quit the talks.

“I want them to stay seated in the dialogue that is beginning. They must have patience,” he said on the radio.

Under constitutional rules, the opposition must secure a referendum before January 10 if it wants to remove Maduro. Otherwise he or his allies will keep power until 2019.

Venezuela is rich in oil but short of food.

An economic crisis sparked by falling crude prices has led to shortages of basic supplies and soaring inflation.

The opposition blames Maduro’s economic management. He calls the crisis a US-backed capitalist conspiracy.

Analysts say there is a risk of violent unrest. Clashes at anti-government riots in 2014 left 43 people dead.

Maduro has a high disapproval rating, according to recent opinion polls.

“The likelihood that the government in negotiations will accept a referendum or early elections is practically zero,” said analyst Luis Vicente Leon, head of pollster Datanalisis.

“Maduro is absolutely certain that would mean handing them his head.”

The president has the public backing of the military high command and control of most state institutions.

The MUD has demanded Maduro loosen his grip on the electoral and judicial authorities.

Donald Trump’s victory in the US presidential election meanwhile adds tension and uncertainty to the situation, analysts say.

Maduro has had a combative stance even towards the more moderate outgoing US leader Barack Obama.

Obama’s administration had boosted contact with Venezuelan authorities in a bid to ease the crisis. But the Democrat leaves office in two months.

“Trump’s aggressive and threatening discourse will be the perfect excuse to strengthen the theory about Venezuela’s external enemies,” Leon said.

Mediators taking part include Vatican envoy Claudio Maria Celli and Spain’s former prime minister Jose Luis Rodriguez Zapatero.

But suspicion and doubt clouded the run-up to the talks.

“We are sceptical. Venezuela needs signs of change,” said leading opposition figure Henrique Capriles.

“We are on the brink. The economic situation is a bomb ready to explode.”

Nicmer Evans, a socialist political analyst and strong critic of Maduro, was also critical of the opposition’s negotiating strategy.

“The opposition is trying to negotiate impossible things,” he said.

Having suspended its street protests against Maduro, the MUD is now trying to “demand that he hand over everything, but offering nothing in return”.