According to the polls, Venezuelans will overwhelmingly vote against President Nicolas Maduro in Sunday’s presidential election, posing the biggest threat his regime has so far seen to its survival. Nobody expects Maduro to accept the results, but neither does anybody know how things will turn out.

After many years of ineffective and internally divisive opposition, the person who has managed to unite Venezuelans under a single ballot is Maria Corina Machado, one of the world’s most admirable political leaders. Although she won the opposition primary by more than 90 percent of the vote, her name is not on the ballot. Sensing vulnerability, the regime disqualified her candidacy. Machado then selflessly backed Edmundo Gonzalez and has organized massive rallies across the country in her campaign to support Gonzalez and restore freedom to Venezuela.

Machado is under no illusion that Sunday’s vote will be free or fair, as she explained in an address to our recent conference in Buenos Aires, “The Rebirth of Liberty in Argentina and Beyond,” which is worth watching. Machado’s appeal is that she represents a clear set of values—those of liberal democracy—and has come to embody sheer dignity and courage in the face of adversity and threats to her life and safety.

For example, Venezuelans remember when, as a congresswoman, she called Hugo Chavez a thief to his face on national television in 2012 and challenged him to explain his disastrous record. They remember too how Chavistas broke her nose in an attack on the very same floor of the Congress the next year. The past year of campaigning has seen even more adversity, with numerous members of her team being abducted or arrested or who have had to seek foreign refuge.

Throughout her many years of activism and political involvement, her message has been consistent and clear-eyed. At a Cato policy forum in 2009, for example, she explained how Chavez’s social policies were failing to achieve their supposed goals and why socialist policies would not work. Venezuelans have heard her stick to her principled message in favor of market democracy and limiting power over the years and that too has bolstered her credibility as the country’s economic, social, and political crisis deepens.

Maria Corina Machado’s achievement in uniting her country against tyranny has already been great. No matter what the outcome, the regime and its legitimacy have already been weakened as a result.