Influencing a polarized and connected legislature

When can an interest group exploit polarization between political parties to its advantage? Building upon Battaglini and Patacchini (2018), we study a model where an interest group credibly promises payments to legislators conditional on voting for its preferred policy. A legislator can be directly susceptible to other legislators and value voting like them. The overall pattern of inter-legislator susceptibility determines the relative influence of individual legislators, and therefore the relative influence of the parties. We show that high levels of ideological or affective polarization are more likely to benefit the interest group when the party ideologically aligned with the interest group is relatively more influential. However, ideological and affective polarization operate in different ways. The influence of legislators is independent of ideological polarization. In contrast, affective polarization effectively creates negative links between legislators across parties, and thus modifies the relative influence of individual legislators and parties.