Balancing constituency representation and party responsiveness in the US Senate: the conditioning effect of state ideological heterogeneity

Spatial proximity theories of representation focus on the importance of the average views of constituencies in guiding legislators’ decisions. However, legislative scholars also identify political parties as central in structuring behavior. We present and test a theory of how legislators might resolve this tension. We propose that heterogeneity in constituent preferences conditions how legislators balance the (sometimes) rival pressures of constituency and party. Specifically, greater preference heterogeneity weakens the impact of the average constituency views on roll-call behavior while strengthening the impact of party. We show support with data from the US Senate and discuss the implications for democratic representation.