The influence of campaign donors on political polarization has long been debated in American politics. This research examines how ideological heterogeneity among supporters affects legislative behavior and voting patterns across state-level representatives.

Our Puzzle: Do diverse donor bases lead to more moderate or polarized policy positions? Many assume heterogeneous support prevents extreme views, but evidence remains mixed.

To answer this question clearly, we developed a new measurement model for ideological heterogeneity in campaign contributions. Using regression analysis on data from the American States dataset (1985–2014), we estimate donor ideology across 50 states and their congressional districts.

Key Findings:

Our results show that while donors may be ideologically diverse, state legislators still adopt positions reflecting dominant party ideologies. Campaign contributions correlate with increased polarization, even when donor bases are mixed.

Why It Matters:

These findings challenge the notion that ideological diversity in support necessarily moderates political extremism. Instead, they suggest money from any ideology can amplify polarizing effects.