Supplementary materials to: Talking about what would happen versus what happened: Tracking Congressional speeches during COVID-19

In counterfactual thinking, an imagined alternative to the reality that comprises an antecedent and a consequent is widely adopted in political discourse to justify past behaviors (i.e., counterfactual explanation) or to depict a better future (i.e., prefactual). However, they have not been properly addressed in political communication literature. Our study examines how politicians used counterfactual expressions for explanation of the past or preparation of the future during COVID-19, one of the most severe public health crises. All Congressional speeches of the Senate and House in the 116th Congress (2019-2020) were retrieved, and counterfactual expressions were identified along with time-focusing in each speech, using recent advances in natural language processing (NLP) techniques. The results show that counterfactuals were more practiced among Democrats in the Senate and Republicans in the House. With the spread of the pandemic, the use of counterfactuals decreased, maintaining a partisan gap in the House. However, it was nearly stable, with no party differences in the Senate. Implications of our findings are discussed, regarding party polarization, institutional constraints, and the quality of Congressional deliberation. Limitations and suggestions for future research are also provided.