CARACAS • Venezuela's presidential election race has begun with favourite and incumbent Nicolas Maduro signalling a nationalist, "anti-Trump" campaign while his demoralised foes scramble to find a viable candidate for a vote they predict will be unfair.

Critics of the 55-year-old Maduro, who succeeded Mr Hugo Chavez in 2013, say he has ruined a once-prosperous oil economy, turned Venezuela into a dictatorship and skewed the election system to perpetuate power for his Socialist Party.

Government officials say they are fighting a United States-led right-wing conspiracy determined to end socialism in Latin America, hobble Venezuela's economy and steal its oil wealth.

"Donald Trump is not the boss of Venezuela!" thundered Mr Maduro at a rally late on Tuesday. He spoke hours after the pro-government Constituent Assembly, a legislative superbody, announced the vote would be held by April 30.

Mr Maduro confirmed on Wednesday that he would stand for re-election. His approval ratings have plunged during a crushing four-year recession caused by failed economic policies such as decade-old currency controls and the fall in global oil prices since 2014.

US Vice-President Mike Pence called Mr Maduro a "dictator" on Twitter on Wednesday, adding that snap elections were "undemocratic, unconstitutional, and globally opposed".

Foreign sanctions against Mr Maduro's government, including a US prohibition on investors' dealing with any new Venezuelan debt, have exacerbated the grim panorama as millions suffer food and medicine shortages and the world's highest inflation.

But with Mr Maduro having survived massive protests last year and consolidated his grip, the international pressure has now given him a powerful rallying cry to seek re-election. "The people rule in Venezuela, not empires," he said at Tuesday's rally, going straight into campaign mode. "I'm ready... We're going to win big."

Venezuela's opposition, which brought hundreds of thousands of people onto the streets last year in an attempt to oust Mr Maduro, is in a quandary. Its most popular figures - including Leopoldo Lopez and Henrique Capriles - are prevented from standing. Some are in jail while others are in exile or barred from politics.

"The election will be held on Maduro's terms, allowing him to ensure his victory," the Eurasia consultancy said.

"All of this will come at a cost of increased international isolation, something that the government seems willing to stomach if the trade-off is to lose power."

REUTERS