Previous studies have shown that trade politics in the US Congress is determined by congressional partisanship, ideology, and constituents' economic interests. In this article, I utilize the case of the Trans-Pacific Partnership (TPP) and the theoretical perspective of the literature on China's trade shock to investigate how these three factors affected US congressional representatives' support for the TPP in 2015. Based on the results of quantitative analysis, this article finds that congressional support for the TPP was determined by partisanship, ideology, and their electoral district's trade with China. Specifically, Republican and conservative congressional representatives were more likely to support the TPP than Democrats and liberals. Districts importing more from China were more likely to support the TPP. These findings enrich our understanding of trade politics in the US Congress in the age of US-China competition.