TikTok is a video-sharing social networking service, whose popularity is increasing rapidly. It was the world's second-most downloaded app in 2019. Although the platform is known for having users dancing, lip-syncing and showing off their talents, there is an increase in videos designed to express political opinions. In this study, we perform the first evaluation of political communication on this platform. We collect a set of US Republican and Democratic partisan videos and investigate how users communicate with each other. With the help of computer vision, natural language processing, and statistical tools, we illustrate that political communication is much more interactive on TikTok in contrast to other social media platforms, with users combining multiple information channels to spread their messages. We show that political communication takes place in the form of communication trees since users generate branches of responses on existing content. Finally, we investigate user demographics and their interactions with opposing views. We find that partisan users from both parties are young and behave similarly on the platform. We also find that Republican users generate more political content, and their videos receive more reactions. However, Democratic partisans engage significantly more in cross-partisan discussions.