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Disentangling the Role of Ideology and Partisanship in Legislative Voting

Fri, September 1, 12:00 to 1:30pm, Hilton Union Square, Franciscan D


In this paper, we separate the effects of partisan loyalty and personal ideology on legislators voting behavior. First, we place voters, legislators, and party leaders on a common ideological space using a unique survey of Argentine lawmakers and voters conducted in 2008 and the Bayesian implementation of the Aldrich-McKelvey method. Next, we calculate ideal points for the legislators included in the survey using their observed roll-call votes. Finally, to identify the influence of political parties on legislators’ behavior we use a structural equation model to account for the separate effects of constituents’ ideology, party cohesion, and party discipline on legislative voting. Our findings indicate that the weight placed on the party line is the most important determinant of legislative voting: legislators give 5 to 6 times as much weight to the preferences of their party whip relative to their own ideology. The analysis of legislators’ recovered ideal points indicates that the party influence follows a government-versus-opposition logic rather than a purely ideological divide. We thus conclude that, in the Argentine case, the conflict between the government and the opposition left little room for legislators’ ideological preferences to affect their voting behavior.