Working through the issues: how issue diversity and ideological disagreement influence coalition duration

Issue salience and diversity direct a range of outcomes such as voting behavior and public policy. Studies, however, have yet to fully integrate theoretical or empirical expectations for the effect of issue salience on coalition stability. By focusing on the mechanism linking parties’ preferences to policy-making, I propose that parties with more diverse platforms provide coalitions greater room to negotiate, whereas parties focusing on a small number of issues exacerbate ideological tensions. Issue diversity becomes important once parties exhaust opportunities to make the initial, easy policy compromises. Using evidence from 299 coalitions in 24 European countries, I find that issue diversity in parties’ platforms moderates the effect of disagreement. Using a non-proportional hazard analysis, I find that the effect of issue diversity varies over the coalition’s lifecycle. Governments with parties willing to negotiate over a larger range of issues decrease the risk that disagreements will result in coalition termination.