  The median voter theorem has long been the default model of voter behavior
and candidate choice. While contemporary work on the distribution of political
opinion has emphasized polarization and an increasing gap between the "left"
and the "right" in democracies, the median voter theorem presents a model of
anti-polarization: competing candidates move to the center of the ideological
distribution to maximize vote share, regardless of the underlying ideological
distribution of voters. These anti-polar results, however, largely depend on
the "singled-peakedness" of voter preferences, an assumption that is rapidly
loosing relevance in the age of polarization. This article presents a model of
voter choice that examines three potential mechanisms that can undermine this
finding: a relative cost of voting that deters voters who are sufficiently
indifferent to both candidates, ideologically motivated third-party
alternatives that attract extreme voters, and a bimodal distribution of voter
ideology. Under reasonable sets of conditions and empirically observed voter
opinion distributions, these mechanisms can be sufficient to cause
strategically-minded candidates to fail to converge to the center, or to even
become more polarized than their electorate.
