Degree Name

Master of Arts

Department or Program

Political Science


Mulligan, Kenneth C.


This study measures the influence of a representative’s personal ideology, constituent ideology and interest group contributions on the voting behavior of United States Senate members. Theory holds that district preferences exert the most salient influence on voting behavior of public officials at the national level. Conversely, I propose that the personal ideological orientation of a United States senator influences his voting behavior to a greater extent than constituent preferences and political interest group contributions and that a representative’s personal ideology is synonymous with the values and ideas of his political party. I base my argument on the rational assumption that representatives who establish party loyalty through their voting record as well as through financial contributions to other candidates within their party will attain respect, promotion, endorsements and financial backing from party leadership. Quantitative data is taken from roll call votes in 2013 listed on and from DW Nominate scores, which places senators’ party ideology on a liberal-conservative scale. Data targets a single issue: gun legislation. I also use quantitative data aggregated on a state-by-state basis from the Cooperative Congressional Election Survey in 2012 to obtain the percentage of constituents favoring stricter background checks and gun control regulations in each state. The study assumes that constituents will vote for candidates who share their policy ideologies. Finally, I use to look at state-level data to track the size of political interest group donations to United States senators.