This book integrates spatial and behavioral perspectives - in a word, those of the Rochester and Michigan schools - into a unified theory of voter choice and party strategy. The theory encompasses both policy and non-policy factors, effects of turnout, voter discounting of party promises, expectations of coalition governments, and party motivations based on policy as well as office. Optimal (Nash equilibrium) strategies are determined for alternative models for presidential elections in the US and France, and for parliamentary elections in Britain and Norway. These polities cover a wide range of electoral rules, number of major parties, and governmental structures. The analyses suggest that the more competitive parties generally take policy positions that come close to maximizing their electoral support, and that these vote-maximizing positions correlate strongly with the mean policy positions of their supporters.

We present a unified model of turnout and vote choice that incorporates two distinct motivations for citizens to abstain from voting: alienation from the candidates, and indifference between the candidates. Empirically, we find that alienation and indifference each motivated significant amounts of voter abstention in the 1980-1988 U.S. presidential elections. Using model-based computer simulations-which permit us to manipulate factors affecting turnout-we show that distinguishing between alienation and indifference illuminates three controversies in elections research. First, we find that abstention because of either alienation or indifference benefited Republican candidates, but only very modestly. Second, presidential elections involving attractive candidates motivate higher turnout, but only to the extent that abstention stems from alienation rather than from indifference. Third, paradoxically, citizens' individual-level tendencies to abstain because of alienation are strongly affected by their evaluations of the candidates' policies, whereas aggregate turnout rates do not depend significantly on the candidates' policy platforms.

A unidimensional spatial model of multiparty parliamentary elections under proportional representation is presented, in which parties project that the median parliamentary party will implement its policy position. The parties are assumed to be uncertain about the electoral impact of valence issues relating to party elites’ images of competence, integrity and charisma. The assumptions of the model, highlighting the importance of the median party in parliament, are consistent with empirical work by McDonald and Budge. Under them, the existence of a Nash equilibrium under quite general concavity conditions is proved and it is shown that parties will moderate their positions when their valence images deteriorate. Computations of party equilibria are reported. The model and its implications for policy-seeking parties with results on vote-seeking parties can be contrasted with that recently reported by Schofield and Sened.

Most spatial models of two-candidate competition imply that candidates have electoral incentives to present similar, centrist policies. We modify the standard Downsian model to include three observations supported by empirical research on American elections: that voters are prepared to abstain if neither competitor is sufficiently attractive (abstention due to alienation) or if the candidates are insufficiently differentiated (abstention due to indifference); that voters are influenced by factors such as education, race, and partisanship that are not directly tied to the candidates' positions in the current campaign; and that voters' nonpolicy characteristics correlate with their policy preferences. Our results suggest that voters' turnout decisions and their nonpolicy characteristics, even if the candidates in the course of a campaign cannot manipulate the latter, are nonetheless necessary for understanding candidates' policy strategies.

In the United States and Latin America, candidates for national and state-level office frequently must win primary elections in order to advance to the general election. We model policy and valence issues for office-seeking candidates facing such two-stage elections. We determine a Nash equilibrium for the candidates' optimal strategies, and we find that holding a primary is likely to increase a party's chances of winning the general election, particularly in situations where valence issues that involve the candidates' campaigning skills and that are not known prior to the campaign are more salient than policy issues. Furthermore, we find that primary elections are especially likely to benefit parties that expect to be underdogs in the general election. Our conclusions are directly relevant to U.S. politics and by extension to the strategic decisions that many Latin American parties currently confront, about whether it is strategically desirable to hold primaries.