Previous sociological studies demonstrated that U.S. multinational corporations (MNCs) had durable political power to motivate U.S. trade policy. However, why did the United States switch from a “free trade” to an “America First” trade agenda? Economists and political scientists argue that protectionist voters elected the protectionist candidate—Trump. An alternative sociological explanation is that U.S. MNCs lost political power to competing stakeholder groups. The article uses qualitative and quantitative methods to test these competing theories using the case study of the U.S. withdrawal from the Trans-Pacific Partnership (TPP). The article argues that both theories are necessary, and neither are sufficient. The United States withdrew from the TPP because increasing negative effects of trade and investment in the United States reshaped trade politics, especially on the republican side; however, power relations between stakeholder groups had to shift as well. U.S. MNCs lost political influence over trade policy to new domestic manufacturing organizations and their networks with labor and fair trade coalitions.