Why Perceived Policy (In)congruence Matters for Durable Voter Attachment: The German Greens Under a New Wave of Environmental Politicization

Recent years have been characterized by a new wave of environmental politicization, most notably expressed through the world-wide protest activities of the Fridays for Future movement. In the German case, the rise of environmental issues has been accompanied by an increasingly successful Green party which simultaneously broadened its issue agenda. This paper investigates voter attachment of (former) Green core voters amid these developments. As the Green party shifts from a niche to a mainstream profile, core voters may perceive a policy incongruence with their strong pro-environmental stance, potentially leading to voter detachment. Using individual-level panel data from the German Longitudinal Election Study from 2017 to 2021, we analyze how perceived policy incongruence on environmental issues influences voter defection. Our findings indicate that while pro-environmental voters do not automatically turn away from the party when perceiving incongruence, they are more likely to do so when environmental issues are personally and publicly highly salient. This study highlights the impact of issue politicization and party mainstreaming on (former) core voter support, providing insights into the challenges faced by parties expanding beyond their traditional niche when their owned issue is strongly politicized.