Simultaneous elections in a polarized society make single-party sweeps more likely
Pradeep Dubey, Siddhartha Sahi
TL;DR
The paper addresses how simultaneous elections in polarized societies influence macro-level outcomes by increasing the likelihood of single-party sweeps. It models voters with fixed party preferences and turnout probabilities, showing that coarser or staggered polling schedules raise the chance that one party wins all contests, across major electoral systems. The key technical contribution is a generalization of the Harris inequality to an n-function setting, which underpins the sweep results. This scheduling-driven, systemic mechanism operates independently of leader popularity and has practical relevance for debates like One Nation One Election and related governance considerations.
Abstract
In a country with many elections, it may prove economically expedient to hold multiple elections simultaneously on a common polling date. We show that in a polarized society, in which each voter has a preferred party, an increase in the simultaneity of polling will increase the likelihood of a single-party sweep, namely, it will become more likely that a single party wins all the elections. In fact we show that the sweep probability goes up for \emph{every} party. Thus the phenomenon we describe is independent of the ``coattail'' or ``down-ballot'' effect of a popular leader. It is a \emph{systemic} and \emph{persistent} macroscopic political change, effected by a combination of political polarization and simultaneity of polling. Our result holds under fairly general conditions and is applicable to many common real-world electoral systems, including \emph{first-past-the-post} (most voters) and \emph{party list proportional representation} (most countries). In the course of our proof, we obtain a generalization of the well-known Harris correlation inequality.