Measuring factional conflict: A comparative approach using party leadership contests

Intra-party factions have attracted increased scholarly attention in the twenty-first century as party systems have fragmented. Yet, we lack a comparative approach to identify factional conflict. We offer a novel, qualitatively derived approach to operationalize factional conflict using patterns of support in leadership contests. We apply our approach to an original dataset of 205 leadership contests from 29 parties in six consolidated democracies between 1990 and 2024. Empirically, we find that rates of factional conflict in mainstream parties increased from the first decade of the twenty-first century onwards. Niche parties had significantly less factional conflict during this period. We discuss the benefits and limitations of our approach, implications of our empirical finding, and directions for future development and application.