Turnout and Invalid Voting in Brazilian Municipal Elections: A Runoff Voting System Tale

ABSTRACT This paper assesses the impact of Brazil's hybrid mayoral voting system on voters' choices and examines the shift in blank, null, and turnout between the first and second rounds. Using fixed‐effects and RDD techniques over 5570 municipalities between 2000 and 2020, this study shows that runoff voting generates more abstention and invalid voting than one‐round voting. The restriction of choices in the second round is found to be the main reason to alienate voters from the electoral process. Moreover, the percentages of blank, null, and turnout in the first round proved to have a significant persistent effect on the second round.