Who Donates to Party Switchers?

What are the causal effects of legislative party switching on campaign fundraising? Using a selection-on-observables strategy (a first in the study of U.S. party switchers), we demonstrate that relative to other similarly situated legislators, party switchers rely more heavily on partisan and ideological, out-of-district individual donors, and direct party contributions. In short, switchers—in trying to alleviate the electoral costs of switching—rely disproportionately on donors motivated to protect vulnerable incumbents of a particular party. We conclude with a discussion of how these dynamics reinforce partisan polarization and raise normative questions about representation and the role of the “surrogate constituency.”