Identifying the “Downsian Ceiling”: When Does Polarization Make Appealing to One’s Base More Attractive than Moderating to the Center

There are two basic strategies in which candidates in two-party partisan contests may engage: (1) the Downsian strategy of tailoring their platform to appeal to the views of the median voter in the electorate, and (2) seeking to motivate high turnout levels among their key supporters (their partisan base) by taking positions popular with that base. High polarization alters expected payoffs from each strategy by enhancing party loyalty, on average, and increasing the influence of voters with more extreme views. Thus, as polarization rises, expected gains to be made from mobilizing turnout among one’s base increase while expected gains to be made from moving in a more moderate direction decrease. Applying a spatial model analysis of parties undergoing polarization under the threat of abstention, we find that Downsian convergence to the overall median is maintained as long as polarization remains below a “Downsian ceiling,” but beyond that ceiling, ever more divergent party strategies are optimal. These Nash equilibrium locations can be much closer to the medians of the respective party bases than to the overall median of the electorate. Hence increases in polarization should foster an emphasis on a “mobilize the base strategy.”