The informal rules of candidate selection and their impact on intra-party competition.

While the literature highlights the relevance of informal rules for candidate selection, empirical research has mainly focused on formal rules and procedures. This article contributes to our understanding by investigating how the informal rules employed by political parties impact on intra-party competition. Using the example of district nominations in Germany, and based on a longitudinal mixed methods design, the inductive analysis reveals five central informal rules: the Incumbency Rule, the Information Rule, the House Power Rule, Fairness Rules and Power-sharing Rules. These rules shape the expectations and behavior of those involved in candidate selection and have a significant impact on various aspects of intra-party competition. They decrease the number of aspirants, reduce intra-party conflict and emphasize the role of local party leaders in organizing and controlling intra-party competition. [ABSTRACT FROM AUTHOR]