Does the partisanship of poll workers affect electoral outcomes? Many countries use partisan and adversarial vote-counting systems where poll workers are party representatives and mutual control is expected to provide fairness. Yet in countries with dominant party regimes, parties often have de facto unequal capacities to send representatives to all booths. Analyzing the 2018 general elections in Paraguay, we estimate that partisan poll workers decrease an opposing party's vote share by up to 2 percentage points (pp) and increase theirs by up to 1 pp. Our analyses also demonstrate how incentives for electoral manipulation vary by electoral system. Dominant parties' partisan poll workers collude against smaller parties more often in proportional representation races. In contrast, single-winner plurality voting yields less collusion because the winner-take-all aspect of these races make collusion difficult. Our results have practical implications for politicians and policymakers, as well as theoretical implications for elections in developing democracies.
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