Partisan Cohorts, Polarization, and the Gingrich Senators

Abstract

Although the “Gingrich Senators” thesis solves a vexing issue, a broader theoretical question remains: Why does the House have a polarizing effect on its members that seems to persist even after a representative wins election to the Senate? In the first section, I propose that lawmakers learn partisan norms in the House and simply continue those extreme behavioral routines after switching chambers. And in the second part, I test possible sources of this effect. Results show that senators who came from the House display greater ideological extremism if they (a) served in the House within an extreme partisan cohort and (b) won election to the Senate after representing a partisan district. In contrast, serving within a polarized chamber and during periods of divided party control have no long-term effects on a senator’s ideological extremism. Robustness checks reveal that the effect of a senator’s House partisan cohort persists even when we control for his/her ideological extremism before winning election to the House as well as selection effects caused by electoral dynamics. Additional analyses show that the partisan cohort effect is the largest determinant of partisan learning, exists throughout most of congressional history, is strongest when the parties are homogeneous, and persists for much of a senator’s career. As a whole, the results show that the House’s effect on Senate polarization is not due to a single person or a function of chamber polarization. Rather, the “Housification of the Senate” is a consequence of cohort socializing effects and is observable throughout congressional history.