How One Corruption Scandal Cost Germany's CDU/CSU Four Percentage Points

What Happened and Why It Matters

In March 2021 several national MPs from Germany's governing CDU/CSU were publicly accused in a public-procurement corruption scandal. Arndt Leininger and Lukas Rudolph ask whether voters punish an entire party for the misconduct of a few individual politicians — and whether that punishment travels across levels of government and organizational boundaries within the party.

Quasi-Experimental Strategy

The authors exploit the timing of the allegations, which surfaced shortly before two state elections, to create a quasi-experimental test. They compare pre-scandal postal votes with post-scandal in-person (urn) votes and implement a difference-in-differences design to isolate the scandal's effect on party vote shares from other trends. This design leverages the fact that some ballots were cast before the allegations became public while others were cast afterward, producing a plausibly exogenous source of variation in exposure to the scandal.

Key Findings

• The scandal produced a measurable decline in the CDU/CSU vote share: about a 4 percentage point loss for the party in the affected contests.
• This electoral damage occurred even though the state elections were at a different level of government than the implicated national MPs.
• Voter punishment extended to a state party chapter that had no implicated MPs, indicating brand-level spillover rather than purely local retaliation.

Additional Tests and Conditions

Leininger and Rudolph further probe enabling conditions that shape whether individual politicians' wrongdoing spills over onto their party. They examine how timing relative to voting, institutional level, and the presence (or absence) of implicated local representatives affect the magnitude and reach of electoral punishment, and they discuss robustness checks that support their causal interpretation.

Why This Matters for Scholars and Practitioners

The results show that scandals surrounding individual parliamentarians can damage a party's broader electoral brand, even across government levels and in organizational units without direct involvement. The findings sharpen understanding of accountability mechanisms in democracies and have implications for party reputation management, candidate vetting, and the timing of disclosures ahead of elections.