CARACAS, Venezuela — In the years since the Venezuelan crisis began, Yajaira Paz, 35, has lost nearly everything to its fallout: her mother, dead from a heart problem she could not afford to treat; her brothers, to migration; her faith in democracy, to the nation’s crippled institutions.

And so, on Sunday, when Venezuelans head to the polls to choose new lawmakers, she will not cast a vote. The election, she said, is nothing more than a charade, one designed “to make the world believe there is freedom in Venezuela.”

Venezuelans will cast ballots Sunday in elections that critics are calling a theater piece meant to lend a veneer of legitimacy to the government of President Nicolás Maduro, who has spent the last seven years jailing opponents, tearing apart opposition parties and using extrajudicial killings to stifle dissent.

If his allies win control of the newly expanded 277-seat National Assembly, as they are widely expected to do, Mr. Maduro will take over the last major opposition-held political institution in the country, solidifying his grip on the nation.

The election could significantly weaken Juan Guaidó, the opposition leader and legislator who in 2019 launched a bold effort to oust Mr. Maduro by declaring himself the country’s interim president, a move backed by the United States and dozens of other countries.

But Mr. Guaidó’s bid for power failed to gain traction, and his claim to the presidency is rooted in his being the head of the current National Assembly.

Following the selection of a new assembly, Mr. Guaidó will no longer be a legislator — he is boycotting the vote — making it increasingly difficult for foreign nations to recognize him as Venezuela’s president. This has left many Venezuelans who are eager for change calling for new opposition leadership, with some analysts saying that the moment for his coalition, sometimes called the G4, is ending.

“The idea that the G4 is the sole representative of the Venezuelan opposition is dead,” said Sergio Jaramillo, a former Colombian official who advises on peace negotiations around the world. “A much more inclusive approach is needed.”

Mr. Guaidó and his allies say they are boycotting the vote to avoid legitimizing a process that would be used to prop up Mr. Maduro. Instead, they will hold their own event, online and in-person, in which Venezuelans can register their desire to change the government. Mr. Guaidó has called it an “alternative to fraud.”

He and his allied lawmakers, elected in 2015, have said they will continue to claim to be the legitimate legislature, becoming a sort of congress frozen in time.

This has drawn criticism from some opposition politicians who have decided to run on Sunday, declaring that no one can expect to effect change if they’re not at the table, no matter how lopsided the table.

“We can’t renounce the vote as a means of struggle and an instrument of change,” said Armando Amengual, a dissident candidate running from the state of Carabobo.

He added that Mr. Guaidó’s “vision of change” had been exhausted.

Independent observers have declared the election deeply flawed.

In a report on election conditions published by the Universidad Católica Andrés Bello of Venezuela and an intergovernmental organization, investigators described how Venezuela’s top court this year stripped three of four main opposition parties of their leadership, allowing the parties to be co-opted by politicians friendlier to the government.

In what the report’s authors called a clear constitutional violation, the country’s electoral body this year increased the number of seats in the National Assembly from 167 to 277 in an effort to splinter the opposition, “paving the way for the government party to win.”

And among other problems, there is widespread fear among voters that they will be stripped of food benefits if they don’t cast ballots, or don’t vote for Maduro-backed candidates, rumors the government has encouraged.

Diosdado Cabello, a top figure in Mr. Maduro’s party, joked recently at a campaign event that mothers should threaten members of their household: “Those who don’t vote, won’t eat.”

No major international organizations will monitor the vote. Mr. Maduro had invited the European Union to observe the process, but officials declined, saying that he had not given them enough time to organize a proper mission.

Despite fears of government backlash, turnout is expected to be low, with many people afraid to vote because of the coronavirus, or because they see voting as pointless.

In many areas around the country, the deepening economic crisis, and the failure of the U.S.-backed effort to oust Mr. Maduro, has heightened feelings of abandonment and political impotency.

“Who cares if there are elections or not, if Donald Trump or the new president of the United States helps us or not,” said José Urdaneta, 56, a driver who lost his job amid the pandemic and will not vote on Sunday.

None of that would make a difference, he went on. “Here, we fend for ourselves or we die.”

The election comes at a particularly difficult time for Venezuela. Hunger, joblessness, gasoline shortages and a breakdown of the health care system have only worsened with the coronavirus.

The gap between the poor and a small group of wealthy, government-connected individuals — often called “enchufados,” or the plugged-in crowd — has widened as U.S. dollars have increasingly replaced bolivares as the common currency, and prices of everyday goods have skyrocketed.

Ninety-two percent of respondents to an October poll by the firm Datanalisis had a negative view of the country’s situation, the highest number since 2011.

Mr. Maduro’s disapproval rating was 82 percent, while Mr. Guaidó’s was 67 percent, near records for both of them.

Ms. Paz, the woman who had lost so much amid the country’s decline, once had a decent life as a shop manager. She left that job to care for her sick mother, then watched with a broken heart as her brothers, who had fled to Peru, struggled to raise the money for their mother’s care.

The state, its health system in collapse, offered no help, and they never raised enough for a critical operation at a private hospital.

Her mother died of a heart attack in December. Ms. Paz is now preparing to leave Venezuela for Peru to join her siblings.

“No one will get me out of the house to vote on Sunday,” she said recently, waiting at a government office to get an identity card she would need to travel. She was 1,576 in line.

“What will they threaten me with? What can they take from me, if they give me nothing? They have already taken everything.”

Sheyla Urdaneta contributed reporting from Maracaibo, Venezuela, and Tibisay Romero from Valencia, Venezuela.