Working Paper: NBER ID: w3663
Authors: Alberto Alesina; Morris Fiorina; Howard Rosenthal
Abstract: The last three decades have witnessed a sharp increase in the number of states with spilt Senate delegations, featuring two senators of different parties. In addition, there is evidence that senators of different parties do not cluster in the middle: they are genuinely polarized. We propose a model which explains this phenomenon. Our argument builds upon the fact that when a Senate election is held, there is already a sitting senator. If the voters care about the policy position of their state delegation in each election, they may favor the candidate of the party which is not holding the other seat. We show that, in general: (1) a candidate benefits if the non-running senator is of the opposing parry; (2) the more extreme the position of the non-running senator, the more extreme may be the position of the opposing party candidate. Our 'opposite party advantage' hypothesis is tested on a sample including every Senate race from 1946 to 1986. After controlling for other important factors, such as incumbency advantage, coattails end economic conditions, we find reasonably strong evidence of the 'opposite party advantage.'
Keywords: Senate elections; Polarization; Split delegations
JEL Codes: D72; H40
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| Presence of a non-running senator from the opposing party (D72) | Likelihood of success for the candidate from the opposing party (D79) |
| Position of the non-running senator (D72) | Position of the opposing party candidate (D79) |
| Presence of a non-running senator from the opposing party (D72) | Likelihood of a split delegation (D79) |
| Ideological extremity of the non-running senator (D72) | Likelihood of a split delegation (D79) |