We test the Pivotal Voter Model in a real-world setting: a mid-term election in Argentina. To manipulate the perception of being more or less pivotal, we send letters to citizens that did not vote in the mandatory primary elections, making more/less salient how relevant their vote could be to change the result of the election. We designed a randomized controlled trial with three arms, each of them consisting of 6,000 citizens. Two treatment arms will receive letters by postal mails, while the control will not receive any letters. The content of the treatment 1 letter will emphasize in a relatively neutral way the importance of voting. The content of the treatment 2 letter will explicitly say that the vote of the individual that received the letter is important to change the result of the election. It will also show a graph indicating that if less than half of the citizens that did not vote in the primary, showed and vote for the opposition candidate, they will win the election. All the letters will be signed by the candidate of the opposition party. Our main outcome is turnout (at the individual level).