CARACAS, Venezuela (AP) — Venezuelans get a chance Sunday to pick who they think can end the decade-long crisis-ridden presidency of Nicolás Maduro.

They will cast ballots in a primary election independently organized by the country’s opposition despite government repression and other obstacles.

The contest is in itself an exercise in democracy because it required the deeply fractured opposition to work together to give the South American country its first presidential primary since 2012. But it could prove an exercise in futility if Maduro’s government wishes.

While the administration agreed in principle at midweek to let the opposition choose its candidate for the 2024 presidential election, it also has already barred the primary’s frontrunner, Maria Corina Machado, from running for office and has in the past bent the law and breached agreements as it sees fit.

Machado, a former lawmaker who supports free-market policies, is a longtime critic of the governing United Socialist Party of Venezuela. She had maintained a somewhat low profile for years, yet she has dominated the primary race by connecting with the same voters she consistently urged to boycott previous elections.

At one Machado rally, Ismael Martínez, an agriculture worker in the northern city of Valencia, said he previously voted for Maduro as well as the late president Hugo Chávez, but became disenchanted by corruption among some politicians in the current administration.

“I think she is the best candidate,” Martinez said. “She has figured out how to evidence the government’s flaws.”

In addition to Machado, nine other candidates remain in the race. The winner is expected to face Maduro at the ballot box in the second half of 2024. Maduro is looking to extend his presidency until 2030, which would surpass the time that Chávez, his mentor, governed.

Maduro’s allies have ridiculed and dismissed the primary all year long. Still, both the government and its foes have used the contest as a bargaining chip to extract concessions from each other as part of a negotiation process meant to end the country’s complex social, economic and political crisis.

Maduro and an opposition faction backed by the U.S. government agreed during the week to work together on basic conditions for the 2024 presidential election. That prompted the government to release six political prisoners and the Biden administration to lift key economic sanctions.

As part of the agreement, Maduro’s administration and the opposition are supposed to “recognize and respect the right of each political actor to select” a presidential candidate freely.

But in June the government issued an administrative decision banning Machado from running for office, alleging fraud and tax violations and accusing her of seeking the economic sanctions the U.S. imposed on Venezuela last decade.

If Machado wins the primary, the focus will shift to Maduro to see if the government reverses the ban on her seeking office. The U.S., holding up the threat of renewed sanctions, has given Venezuela until the end of November to establish a process for reinstating all candidates expeditiously.

A U.N.-backed panel investigating human rights abuses in Venezuela said last month that Maduro’s government has intensified efforts to curtail democratic freedoms ahead of the 2024 election. That includes subjecting some politicians, human rights defenders and other opponents to detention, surveillance, threats, defamatory campaigns and arbitrary criminal proceedings.

Organizers of the primary have not given an estimate for participation Sunday. Any registered voters in the country can participate, as well as some living abroad.

The primary’s first ballot already was cast in Sydney, Australia. But logistical issues are expected to affect turnout within Venezuela.

Venezuelans typically vote on electronic machines set up at public schools. But the independent commission organizing the primary opted to use paper ballots and to set up voting centers at homes, churches, private schools and other facilities. The locations of many voting centers were still being shifted as of Saturday night.