To date, relatively few academic studies have analyzed congressional candidates’ use of social media in the 2018 U.S. midterm elections. This paper contributes to the literature by conducting a textual analysis of 697 House candidates’ Twitter posts from between January 1st and November 6th 2018. The study focuses on seven key issues – the economy, gun policy, healthcare, immigration, Russia, the Supreme Court, and the Trump presidency – and assesses whether there was a fundamental difference in how Democratic and Republican candidates approached each one. The paper argues that there were partisan differences in social media use and presents two potential explanations: political polarization and how each political party was confronted with unique challenges.