It sounds like they’re moving: understanding and modelling emphasis-based policy change

Position change is an essential feature of political competition. Implicitly, policy change on an issue dimension is often equated with opinion change on specific issues within that dimension. However, in addition to opinion-based policy change, we highlight that parties and candidates can change their overall position by increasing their emphasis on certain opinions within that issue dimension (emphasis-based policy change). Using party manifesto data, we find that parties differ in their use of each type of policy change based on aspects of party organization, particularly the relative power of leaders and activists. Leader-dominated parties are more likely to engage in opinion-based policy change, also in reaction to systemic policy shifts. In contrast, activist-dominated parties tend to change their overall position in reaction to systemic shifts by emphasizing certain positions more. Our approach links salience-based to spatial models of party competition and has broader implications for how we study party competition.