Reining in the Rascals: Challenger Parties’ Path to Power

Challenger parties (i.e., parties without prior government experience) have transformed politics in Europe and beyond, some eventually joining governing coalitions. However, the process by which challenger parties gain access to power remains unclear. We argue that holding elected office in itself improves challenger parties’ chances of entering government. We find support for this expectation in cross-sectional, national-level data. To establish causality, we apply a regression discontinuity design to an original dataset of more than 2,500 elections and 15,000 committee assignments from local governments in Denmark. We show that legislative incumbency increases challenger parties’ access to government in the following electoral term. Lastly, using data from candidate surveys, we show that incumbent challenger parties take more moderate positions and use more mainstream language, consistent with a moderation mechanism. Our findings shed new light on the causes of challenger party success and, more broadly, the centripetal forces driving party system change.