Why all these promises? How parties strategically use commitments to gain credibility in an increasingly competitive political landscape

Abstract Political parties face inherent risks when making election promises, as voters tend to penalize them for unfulfilled commitments. Nonetheless, parties make hundreds of promises. Why do parties engage in such precarious behaviour? I argue that parties employ a policy‐committing strategy when they need to increase the credibility of their policy programme and that they do so more today than previously because the political landscape has changed considerably in many Western democracies (time trend). Moreover, I expect parties to use the policy‐committing strategy more when they operate in a political arena with more competitors (system‐level factor), when they are a mainstream party (party‐level factor) and when they have increased the saliency of an issue (issue‐level factor). I test these four expectations with a unique, new dataset containing 330,850 quasi‐sentences coded from party manifestoes in 11 countries covering several decades of elections. Empirically, I find support for a time trend and show strong effects for the party‐level and issue‐level factors. However, a more competitive environment at the system level makes parties less, not more, likely to use the policy‐committing strategy. These results have important implications for party strategies, issue competition and policymaking in today's democracies.