An Economic Model of Strategic Electoral Rule Choice Under Uncertainty

We study electoral rule choice in a multi-party model where parties are office-motivated and uncertainty over the electoral outcome is present. We show that when all dominant parties (parties with positive probability of winning the elections) have sufficiently good chances of winning, then they agree to change the PR with a more majoritarian rule. We identify the exact degree of disproportionality of the new rule and we prove that it is increasing in the expected vote share of the minority parties (parties with zero probability of winning). The necessary and sufficient conditions for such collusion in favour of a majoritarian rule are: a) the high rents from a single-party government, b) sufficient uncertainty over the electoral outcome and c) ideological proximity of the dominant parties. Keywords: electoral reform, majority premium, single-party government, uncertainty, collusion.