How do Public Officials Learn About Policy? A Field Experiment on Policy Diffusion

Prior research suggests that partisanship can influence how legislators learn from each other. However, same-party governments are also more likely to share similar issues, ideological preferences and constituency demands. Establishing a causal link between partisanship and policy learning is difficult. In collaboration with a non-profit organization, this study isolates the role of partisanship in a real policy learning context. As part of a campaign promoting a new policy among local representatives in the United States, the study randomized whether the initiative was endorsed by co-partisans, out-partisans or both parties. The results show that representatives are systematically more interested in the same policy when it is endorsed by co-partisans. Bipartisan initiatives also attract less interest than co-partisan policies, and no more interest than out-partisan policies, even in more competitive districts. Together, the results suggest that ideological considerations cannot fully explain partisan-based learning. The study contributes to scholarship on policy diffusion, legislative signaling and interest group access.