Electoral equilibrium in double member districts

The median-voter result, and the issue of stability in electoral competition generally, have been examined from a number of different perspectives. Out of all these examinations, however, only a few focus on institutional variables. This essay demonstrates that the median-voter result is robust under a significant institutional change that entails altering the basic assumption of single-member districts. After developing a model of electoral competition in a two-member, first-two-past-the-post district, I show that, if there are three candidates, the set of Nash equilibria is the set of strategy triples (x ₁, x ₂, x ₃), with x ₁ = x ₂ = x ₃ = x*, and such that x* lies between the quantiles of order 1/3 and 2/3. If there are four candidates, I show that a unique Nash equilibrium exists with all candidates adopting a position at the medianvoter's ideal point.