After the country’s reunification German political parties have lost half of their members. Parties respond by expanding intra-party participation. Their goal is to revitalize party organizations and to motivate more citizens to join.
Using original data, we investigate the consequences of an intraparty referendum in a state branch of Germany’s Christian Democratic Union on beliefs and attitudes of party members. We use longitudinal survey data bracketing a nonbinding issue referendum on the party’s stance on same-sex marriage.

Our analysis shows that the referendum had secondary effects that went beyond the referendum’s primary goal of delivering an informal opinion poll to the party leadership. The experience of having a say in an important policy decision fostered members’ sense of party-specific efficacy. The increases were higher among members who did not perceive themselves as efficacious before. Efficacy increased independent of a member’s voting behavior.

Secondly, the referendum provided party members with information on elite positions and stimulated leadership evaluation based on issue congruency. As a result. members use issue-positions as yardstick to evaluate party leaders, if party elites took a stance on same-sex marriage.
Altogether, involvement in intraparty decision-making promotes beliefs and behaviors among the rank and file that are relevant to uphold a vivid and empowering party life.
In the ongoing discussions about expanding intra-party democracy (such as the one we are witnessing in Germany’s Social Democratic Party at the moment), we believe that party members and party leaders can learn from our study about likely effects of opportunities for member participation. Against the backdrop of the study’s relevance to inform these debates, SAGE graciously decided to make the study public for a couple of months.
The study can be obtained here. We also make available the survey data of our two-wave panel study of party members and the syntaxes of our analyses.