On 1 March 2018, President Trump declared a 25% tariff on certain steel imports by invoking Section 232 of the 1962 Trade Expansion Act. The tariff pitted two of America’s most storied and interconnected industries, steel and auto producers, against one another and made allies out of longtime bitter political opponents on Capitol Hill. Later that same year, President Trump doubled down on the steel tariff when he initiated a Section 232 investigation on auto and auto parts imports. The auto industry blasted the proposal, while steel offered its strong support. This paper examines the congressional response to President Trump’s proposed auto tariff. Specifically, we explain why 159 MCs signed a letter opposing the tariff. After controlling for other factors, such as district interests and campaign contributions, we find that ideology matters more than party affiliation on whether legislators signed the auto letter. We also find the second dimension of the DW-NOMINATE score to matter, suggesting the strong presence of intra-party cleavages. Our findings highlight the complex nature of trade policy as a domain of bipartisan agreement amidst broader political polarization and at a time when traditional party platforms on the issue are rapidly changing.