Are Small Donors Polarizing? A Longitudinal Study of the Senate

Abstract

Abstract

Current campaign finance law in the United States does little to redress biases in the donor population. One solution proposed by reformers is to expand the donor base to include a broader and more diverse subset of the population. Yet studies on the effects of “small” money in elections suggest that these reforms may polarize politicians. We conduct a longitudinal study of the effects of campaign finance on ideological sorting in the U.S. Senate in order to understand whether money from small donors causes ideological extremism or whether senators adopt polarizing positions as a strategy for raising money from small donors. The Senate provides a unique window into this question, because senators serve six-year terms and thus enjoy periods of time when they are not immediately accountable to their supporters. We find that a senator's receipts from small donors in previous elections have no effect on their future behavior. Rather, causality appears to flow from the politicians to the donors. Senators' voting behavior leading up to reelection has a significant effect on the money raised from small donors during the reelection at the end of the term. These results suggest that further polarization is not an inevitable consequence of campaign finance reforms that aim to improve equality in representation by expanding access to campaign contributions.