Consistent Biases in Electoral Environments: Evidence from Entry and Exit of Senators

Posted: 13 Aug 2009 Last revised: 18 Jan 2010

Date Written: 2009


In this paper, we compare senators first elected in midterms with those first elected in presidential elections and find them strikingly different: The cohort of senators first elected in presidential elections is consistently more ideologically extreme and party disciplined than the cohort first elected in midterms. This result is surprising in light of empirical evidence suggesting that the electorate in presidential elections is more ideologically moderate and less partisan than the electorate in midterm elections. Furthermore, we find that senators who are ousted or retire from office during the time period around presidential elections are significantly more ideologically moderate and vote more independently than those who exit around midterms. Together, these two empirical regularities suggest that the relatively more moderate electorate in presidential elections generates a more extreme and polarized Senate. These findings suggest that holding concurrent races for office is not outcome neutral and raise policy questions about the timing of elections and ballot initiatives. Our empirical approach is robust to econometric specification and outliers and can be extended to examining models of electoral competition and voting behavior.

Suggested Citation

Halberstam, Yosh and Montagnes, Brendan Pablo, Consistent Biases in Electoral Environments: Evidence from Entry and Exit of Senators (2009). APSA 2009 Toronto Meeting Paper, Available at SSRN:

Yosh Halberstam (Contact Author)

University of Toronto ( email )

Department of Economics
150 St George St.
Toronto, Ontario M5S 3G7

Brendan Pablo Montagnes

Northwestern University - Department of Managerial Economics and Decision Sciences (MEDS) ( email )

2001 Sheridan Road
Evanston, IL 60208
United States

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