The U.S. Senate is a party-polarized institution where divisive political rhetoric stems from the partisan divide. Senators regularly chastise political opponents, but not all senators are equally critical. Research finds that elite party polarization is asymmetrical with greater divergence by Republicans, so I expect Republican senators to mimic that trend with higher levels of partisan rhetoric. To assess the variance in partisan rhetoric, I catalogue senators’ Twitter activity during the first 6 months of the 113th and 114th Congresses, and find that Republicans are more likely to name-call their Democratic opponents and to make expressions of intraparty loyalty, particularly when they are the minority party.

For decades US senators have maximized their limited resources to juggle policy, party politics, and constituents, but the rise of social media sheds new light on how they make these strategic choices. David Mayhew’s seminal study of Congress (1974) argues that lawmakers engage in three types of activities – credit claiming, advertising, and position taking, but equally important is understanding how lawmakers make strategic choices among these activities. Senators’ limited resources and attention forces them to prioritize and make trade-offs among these activities, and new media platforms, like Twitter, offer a window into that decision-making process. This article examines what influences senators’ decisions to publicly communicate these activities on Twitter. By using senators’ daily Twitter activity in 2013 and 2015 as a measure of their individual agenda, I find that senators are most likely to prioritize position-taking activities. Women and committee leaders allocate the most attention to policy positions, but attention to policy may come at a cost. When senators do choose to prioritize policy through position taking, they often make trade-offs that lead to decreased attention to advertising and credit claiming. These activities and the choices among them not only have implications for lawmakers’ behavior in Congress, but also the type of representation and information constituents can expect from their elected leaders.

Understanding how Members of Congress (MCs) distribute their political attention is key to a number of areas of political science research including agenda setting, framing, and issue evolution. Tweets illuminate what lawmakers are paying attention to by aggregating information from newsletters, press releases, and floor debates to provide a birds-eye view of a lawmaker's diverse agenda. In order to leverage this data efficiently, we trained a supervised machine learning classifier to label tweets according to the Comparative Agenda Project's Policy Codebook and used the results to examine the differential attention that policy topics receive from MCs. The classifier achieved an F1 score of 0.79 and a Cohen's kappa with human labelers of 0.78, suggesting good performance. Using this classifier, we labeled 1,485,834 original MC tweets (Retweets were excluded) and conducted a multinomial logistic regression to understand what influenced the policy areas MCs Tweeted about. Our model reveals differences in political attention along party, chamber, and gender lines and their interactions. Our approach allows us to study MCs' political attention in near real-time and to uncover both intra-and inter-group differences.

Hyper-partisanship in Congress extends from the legislative process into lawmakers’ strategic communications, but some partisans are leaning into the political rhetoric. Previous research offers competing explanations for this partisan rhetoric—one ascribed to Republicans’ asymmetric record of heightened partisan politics and another to minority party status within Congress. I investigate these different explanations in the context of congressional social media activity to examine how these competing theories of partisan rhetoric work when explicitly considering the use of partisan labels. I examine senators’ tweets over three Congresses and find support for an asymmetric model of partisan rhetoric; however, minority status relative to the White House and leadership roles bolster this effect. In addition, ideological extremism may explain senators’ willingness to use partisan communication to attack political opponents on social media. These findings expand the scope of existing theories of partisan communication and broadly speak to the intersection of power and party.