How voter distributions, issue ownership, and position influence party emphasis

Background Research regarding party behavior has often be understood through one of two models, (1) the Downsian proximity model, which supposes parties will change positions in order to be most competitive, and (2) the issue salience model, which understands parties to emphasize issues on which it is more competitive. Objectives This study produces a theoretical framework explaining why parties, specifically in a two-party system, emphasize one issue dimension over others. We argue that voter distributions differ across issue dimensions and take one of four general forms: (1) unimodal symmetrical, (2) bimodal symmetrical, (3) unimodal asymmetrical, and (4) bimodal asymmetrical. These distributions determine the nature of an issue dimension as approximating valence or positional. Combined with a party's issue ownership or positional advantage, this determines whether a party emphasizes an issue. An issue owner is expected to emphasize unimodal symmetrical issues, parties with positional advantage are expected to emphasize bimodal asymmetrical issues, and no party should emphasize a bimodal symmetrical issue. The decision to emphasize a unimodal asymmetrical issue is dependent upon whether the issue owner and the party with positional advantage are the same and the long-versus short-term electoral strategy of a party. Methods Data to test this theoretical approach do not yet exist. This theoretical framework is designed to apply to a two-party system. In order to properly test the above expectations, we would need data regarding the distribution of voters along different issue dimensions, as well as the emphases placed on issues by parties. These data must be specific to a two-party system. Conclusion This theory attempted to build a synthesized theory of party behavior based on the Downsian proximity model and the issue salience model. This theory helps explain what issues parties will seek to contest, and which issues become politicized. However, this framework can be extended to explain many questions regarding polarization, party behavior, electoral strategy and political contestation.