Partisan and Ideological Bias Among the Attentive Public: Evidence From Witness Slips in the Illinois General Assembly

ABSTRACT Prior work conjectures that representational gaps may arise due to biases in who contacts politicians. However, direct measures of legislator contact by members of the public are elusive. This study leverages a unique data source to evaluate partisan and ideological bias in public outreach: witness slips in the Illinois General Assembly, online forms individuals can use to support or oppose specific pieces of legislation. Using these expressed positions, we document two key facts. First, witnesses are significantly more supportive of Republican‐sponsored legislation than Democratic‐sponsored legislation. Second, after estimating ideal points for witnesses, we find witnesses are ideologically closer to Illinois Republicans than Democrats. Additional analyses reveal important ideological heterogeneity by policy jurisdiction and interest group affiliation. Together, the results support one theoretical explanation of why legislators systematically mischaracterize public opinion: the views they are exposed to differ significantly from those of the general public.