Members of Congress and the pictures in their heads: The impact of social media on elected officials

The words and actions of elected officials cannot be fully understood without considering their sources of information. This study examines how social media shapes the information members of the US Congress consume and how their partisan media exposure corresponds with legislative behavior. Using Twitter (X) data from those members a partisan media index (PMI) was developed based on the ideological orientation of 35 news outlets, running from extreme left to extreme right. The analysis reveals that most members’ media diets are highly partisan and largely align with party affiliation. Democrats cluster around center-left outlets whereas Republicans show a longer and more right-skewed distribution. PMI scores strongly correlate with member ideology and with subsequent voting behavior. Even when controlling for ideology, partisan media exposure retains a small but significant relationship with voting behavior. The findings indicate that social media following patterns offer meaningful insight into elite polarization and suggest that partisan media ecosystems shape not only public opinion but also the decision-making of political leaders with implications for deliberative democracy.