Venezuela’s authoritarian president, Nicolás Maduro, faces a watershed moment that will determine the fate of his rule and the course of his troubled country.

On July 28, the leader of the nation that holds the world’s largest oil reserves — and yet has seen millions of residents flee amid a crushing economic crisis — will confront his toughest electoral challenge since taking office in 2013.

Polls show that his main opponent, a low-key former diplomat named Edmundo González, is far ahead.

Mr. González is backed by a fiery opposition leader, María Corina Machado, who has captivated voters as she crisscrosses the country, campaigning for him on a promise to re-establish democracy and reunite families separated by migration.

On the other side is Mr. Maduro, a skilled political operator who for years has overcome his unpopularity by tilting the ballot box in his favor. He could use the same tactics to eke out another victory.

Yet, there is a wild card: He could also lose, negotiate a peaceful exit and hand over power.

Few Venezuelans expect him to do that. Instead, political analysts, election experts, opposition figures and four former senior officials in Mr. Maduro’s government interviewed by The New York Times believe, based on his past record, that he is probably mulling multiple options to retain power.

Mr. Maduro’s government could disqualify Mr. González, or the parties he represents, they say, removing his only serious challenger from the race.

Mr. Maduro could allow the vote to go forward, but draw on years of experience of manipulating elections in his favor to suppress participation, confuse voters and ultimately win.

But he could also cancel or postpone the vote, inventing a crisis — a simmering border dispute with neighboring Guyana is one option — as an excuse.

Finally, Mr. Maduro could simply fix the vote tally, analysts and political figures say.

That happened in 2017, when the country held a vote to select a new political body to rewrite the Constitution. The company that provided voting technology, Smartmatic, concluded that the result had “without any doubt” been manipulated — and that Mr. Maduro’s government reported at least a million more votes than had actually been cast. (Smartmatic cut ties with the country.)

Zair Mundaray, a former prosecutor in the Maduro government who defected in 2017, said the country had arrived at a critical moment. Even Mr. Maduro’s followers, he added, “are clear that he is in the minority.”

Whatever Mr. Maduro does, the election will be closely watched by the U.S. government, which has long sought to push him from power, saying it wants to promote democracy in the region, but also looking for a friendly partner in the oil business.

In recent months, the Biden administration’s desire to improve economic conditions inside Venezuela has intensified, as hundreds of thousands of Venezuelans have headed north, creating an enormous political challenge for President Biden ahead of his own re-election bid.

Mr. Maduro has made it clear he has no intention of losing the election, accusing his opponents of plotting a “coup” against him and telling a crowd of followers at a campaign event that “we are going to win by a knockout!” When that happens, he said, his opponents will surely call it fraud.

Representatives of the country’s communications ministry and election council did not respond to requests for comment.

Mr. Maduro, 61, rose to power following the death of Hugo Chávez, the charismatic founder of Venezuela’s socialist project.

A former vice president, he was handpicked by Mr. Chávez in 2013 as his successor. But many Venezuelans predicted that he would fail, saying he lacked his predecessor’s oratorical skills, political savvy, military ties and public loyalty.

They were wrong.

Mr. Maduro has survived a prolonged economic crisis in which year-over-year inflation soared as high as 65,000 percent; several rounds of nationwide protests; a number of coup and assassination attempts; and an effort in 2019 by a young legislator named Juan Guaidó to install a parallel government inside the country.

He has managed to prevent challenges from within the ranks of his own inner circle. And he has navigated punishing U.S. sanctions by strengthening commercial ties with Iran, Russia and China, and, according to International Crisis Group, by allowing generals and other allies to enrich themselves through drug trafficking and illegal mining.

Despite his dire poll numbers, “he has never been stronger,” Michael Shifter, a longtime Latin America expert, wrote in Foreign Affairs magazine last year.

But the election, held every six years, has emerged as perhaps his biggest challenge.

Already, the government is trying to massage the vote in the president’s favor.

The millions of Venezuelans who have fled to other countries — many of whom would probably cast ballots against him — have faced enormous barriers to register to vote. Venezuelan officials abroad, for example, have refused to accept certain common visas as proof of the emigrants’ residency, according to a coalition of watchdog groups.

Election experts and opposition activists say that 3.5 million to 5.5 million Venezuelans eligible to vote now live outside the country — up to a quarter of the total electorate of 21 million people. But just 69,000 Venezuelans abroad have been able to register to vote.

The watchdog groups say denying such a large number of citizens the right to cast a ballot constitutes extensive electoral fraud.

Efforts to undermine the vote are also unfolding inside the country.

The education ministry said in April that it was changing the names of more than 6,000 schools, which are common voting sites, possibly complicating efforts by voters to find their assigned polling places.

Among the lesser known parties on an already complicated ballot — voters will choose among 38 boxes featuring candidates’ faces — is one that uses an almost identical name, and similar colors, to the larger opposition coalition backing Mr. González, potentially diluting his vote.

Perhaps Mr. Maduro’s biggest electoral machination was to use his control of the courts to bar the country’s most popular opposition figure, Ms. Machado, from running in the first place. But she has still mobilized her popularity to take to the campaign trail with Mr. González.

Mr. Maduro’s government, according to the opposition, has targeted the campaign — 37 opposition activists have been detained or gone into hiding to avoid detention since January, according to Mr. González.

Independent electoral monitoring will be minimal. After the government rescinded an offer from the European Union to observe the election, just one major independent organization will monitor the vote, the Carter Center, based in Atlanta.

Luis Lander, director of the Venezuelan Electoral Observatory, an independent group, said in an interview that the election already qualified as among the most flawed in the country in the last 25 years.

Mr. Maduro has raised salaries for public workers, announced new infrastructure projects and ramped up his social media presence. The economy has improved slightly. The president has also been on the campaign trail, dancing with voters across the country, portraying himself as the goofy grandfather of socialism and mocking those who doubted him.

His persistent argument is that U.S. sanctions are at the heart of Venezuela’s economic problems. The country’s socialist movement, despite the economic travails, still runs deep.

During its best years, it lifted millions out of poverty, and it has a powerful messaging arm, with many who will vote for the socialist cause, even if they find fault with Mr. Maduro.

“This is not about a man, but about a project,” Giovanny Erazo, 42, said at a recent get-out-the-vote event.

Others may cast their ballot for Mr. Maduro believing it will bring aid to their families. Loyalists have long been awarded with boxes of food.

Even if Mr. Maduro sabotaged the vote, it is unclear that it would lead to the kind of unrest that could push him from office.

At least 270 people have been killed in protests since 2013, according to the human rights organization Provea, leaving many fearful of taking to the streets. Many frustrated with Mr. Maduro have already voted with their feet by fleeing the country.

Should Mr. Maduro fall short on July 28, he could work with Mr. González to negotiate a favorable departure, some analysts said. The president is wanted in the United States on drug trafficking charges and is under investigation by the International Criminal Court for crimes against humanity. He would want to go to a country where he would be shielded from prosecution.

But Manuel Christopher Figuera, a former director of Venezuela’s national intelligence service, said this scenario was unlikely. “Maduro knows that if he hands over power, although he could negotiate his exit, the rest of this criminal band could not.”

Mr. Figuera fled to the United States in 2019, after joining a failed coup launched by a faction of the party of Mr. Guaidó, the legislator who led a parallel government.

Luisa Ortega, who served as the country’s attorney general under both Mr. Chávez and Mr. Maduro — but fled in 2017 after criticizing the government — warned against a “fatal triumphalism” among people in the opposition.

“An avalanche of votes against Maduro” could defeat him at the polls, she said. “And that won’t necessarily translate into a victory for us.”