The stakes could hardly be higher.

This July, for the first time in more than a decade, Venezuelans will vote in a presidential election with an opposition candidate who has a fighting — if slim and improbable — chance at winning.

Amid an economic and democratic crisis that has led more than seven million Venezuelans to abandon the country — considered among the world’s largest displacements — Nicolás Maduro, the country’s authoritarian president, has done something few thought he would: allowed an opposition candidate with widespread support to appear on the ballot.

Though largely unknown, the challenger is leading in several polls, underscoring how many Venezuelans are hungry for change.

Still, few have illusions that the vote will be democratic or fair. And even if a majority of voters cast their vote against Mr. Maduro, there is widespread doubt that he would allow the results to become public — or accept them if they do.

Venezuela prepares to vote at a moment when the country is facing consequential issues that will resonate far beyond its borders.