CARACAS, Venezuela— Nicolás Maduro won re-election to a six-year term in a Venezuelan presidential election deemed illegitimate by the opposition and foreign governments, paving the way for heavier international sanctions amid widespread discontent over his management of an economy in free fall.
Even before the ballots were counted, opposition candidate Henri Falcón cried foul, saying the election was a sham and calling for a new vote this year.
“We do not recognize this electoral process as valid,” he said. “For us, there were no elections.”
The state electoral board, which is allied with the government, said Mr. Maduro had won 5.8 million votes, or 67% of the total, with nearly 93% of the vote counted, compared to 1.8 million, or 21%, for his main challenger, Mr. Falcón, a leftist former governor and ex-soldier. Mr. Falcón had broken with other opposition leaders who called for a boycott.
Those figures were a far cry from what pollsters had forecast. Most polls before the race gave the edge to Mr. Falcon.
Despite near empty polling stations for much of the day in parts of the country, the election board said turnout was 46%—a number that marked the weakest turnout in a presidential vote in nearly two decades.
“How they underestimated me, but here we are: triumphing,” Mr. Maduro told a crowd of supporters in Caracas. He called his victory “a knockout.”
Surrounded by supporters on a stage, Mr. Maduro celebrated what he called the biggest margin of victory a president had recorded here.
“You have confided in me and I’m going to respond to that infinite confidence, that loving confidence,” he said. “All Venezuela has triumphed. Legitimate elections, accompanied by the only one who can decide the future, the people.”
The victory means Chavismo—the radical leftist movement named for the president’s predecessor, the late Hugo Chávez—will begin a third decade of uninterrupted rule when Mr. Maduro is sworn in for a second term early next year. But it is a government struggling to survive: By the end of the year, the economy will have contracted by 50% since 2013, hyperinflation is expected to top 13,000% and the U.S. has imposed sanctions on much of the top leadership of the government for alleged crimes, including drug trafficking.
Millions of Venezuelans don’t have enough to eat, polls show.
“What we’re living is so hard,” said Yelitza Hernandez, a nurse with two young sons she has trouble feeding. Ms. Hernandez said she would vote, but didn’t want to say for whom.
Mr. Maduro’s victory will likely plunge Venezuela into deeper crisis. It will likely spur more Venezuelans to leave, deepening the cost of looking after refugees for neighbors like Colombia and Brazil. It also means Venezuela’s oil industry will continue to collapse, keeping vital oil off global markets at a time of rising international oil prices.
Phil Gunson, who tracks Venezuela for the International Crisis Group policy analysis organization, said Mr. Maduro faces anarchy.
“What he hasn’t done is anything to fix hyperinflation, food scarcity, the collapse of basic services, how to pay the foreign debt, what to do about all the creditors lining up,” Mr. Gunson said. “He has no plan to fix it and no credible team in place either that could, for example, renegotiate that debt.”
Mr. Falcón had hoped widespread gloom and the appeal of his far-reaching proposals, like adopting the dollar as a way to stop hyperinflation, would swamp voting booths with supporters and force the government to concede. Judging by the empty polling booths all day, that didn’t happen.
In a speech late Sunday, ahead of the election results, he railed against the abstention movement as a lost opportunity. But he also said there were myriad violations, including some 90,000 complaints by his team of electoral monitors who denounced so-called assisted votes, where Socialist Party workers accompanied voters and actually cast ballots for them.
Earlier, U.S. Secretary of State Mike Pompeo issued a tweet calling the elections a “sham.” U.S. leaders had said in recent weeks that more sanctions against Venezuela’s leaders—about 60 of whom have been targeted—could be coming.
State Department spokswoman Heather Nauert said the elections weren’t legitimate, echoing what the European Union and the biggest countries in Latin America have said.
“The United States stands with democratic nations around the world in support of the Venezuelan people and their sovereign right to elect their representatives through free and fair elections,” she said in a Twitter message.
In recent weeks, polls had shown that Mr. Falcón would beat an unpopular president whose five years in office have been marked by the exodus of hundreds of thousands of people to other countries.
But Mr. Falcón’s campaign not only faced the electoral machinery of Venezuela’s Socialist government but also the boycott, which pollsters predicted would hurt him. In addition to facing Mr. Maduro, he had to contend with a second challenger, Javier Bertucci, a televangelist and businessman who siphoned votes from Mr. Falcón. In the end, Mr. Bertucci collected 925,000 votes, or 10.7%, the National Electoral Council said.
Opposition leaders, though, said Mr. Falcón never stood a chance against a government whose leaders have said publicly in speeches that they would never give up power.
Venezuela’s electoral council, stacked with government supporters, in 2016 blocked a recall referendum on Mr. Maduro, though the vote was permitted in the constitution, and two elections last year were marked by widespread fraud. Mr. Maduro’s allies also barred the most popular opposition leaders from running for president.
On Sunday, Mr. Falcón denounced the government for pressuring ordinary people by keeping track of who voted by scanning IDs called Fatherland Cards that are also used to track the state benefits voters receive.
It was one of seven violations of an 11-point agreement that Mr. Falcón had signed with Mr. Maduro in March to ensure as fair a vote as possible. His campaign said the government also failed to allow equal access to state media outlets, technical auditing of the voting machine, include independent international observers and keep pro-government campaigners away from voting centers.
“Today in Venezuela, this has become a virus,” Mr. Falcón said from the central city of Barquisimeto, where he voted and used to be mayor. He criticized the government for “political and social blackmail of a sector of the population whose dignity they’re trying to purchase.”
A former bus driver who received his formative political training in Communist Cuba, Mr. Maduro told voters that he wanted another chance to guide his country. “I will carry out an economic revolution that will shake the entire world,” Mr. Maduro had said at a Thursday rally.
He and his allies have contended the shortages and economic chaos have been the result of U.S. sanctions and local businesses that hoard, explanations rejected by independent economists who blame government policies.
Voting was more robust in the districts where the government has traditionally drawn support. Buses were used to move people to the polls, and teams of pro-government supporters went door-to-door herding residents to the ballot box and reminding them of the monthly food boxes they receive.
“Thanks to Maduro that we get our benefits; before we used to get nothing,” said Victor Vasquez, a 54-year-old truck driver in an east Caracas slum. He feared losing the food and frequent bonuses in the near-worthless bolivar currency if the Socialist leader were to be replaced.
Another government supporter, Humberto Vargas, 72, said Mr. Maduro was “guaranteeing peace” in the face of hostility by the opposition and governments that have opposed the president, such as the U.S. “The United States and the opposition have caused the hunger that many people are suffering,” he said.
Polls, though, show that Mr. Maduro is deeply unpopular and that most Venezuelans blame him and his policies, including price controls, a highly stringent currency exchange and expropriations, for having gutted the economy and decimated a once vigorous middle class.
Anger over what had happened to her country led Carmen Arrechedera, 56, a homemaker, to remain home like so many others.
“No one should have tried to legitimize Maduro but rather leave him alone” in the race, she said. “I don’t believe in the electoral system. It’s fraudulent, and there aren’t even international observers you can confide in. There’s an authoritarian regime in Venezuela that won’t permit itself to be removed from power.”
—Mayela Armas, Maolis Castro and Ryan Dube contributed to this article.