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.