Fundamental dimensions of U.S. trade policy

How many dimensions adequately characterize voting on U.S. trade policy? How are these dimensions to be interpreted? This paper seeks those answers in the context of voting on the landmark 1988 Omnibus Trade and Competitiveness Act. The paper takes steps beyond the existing literature. First, using a factor analytic approach, the dimension issue is examined to determine whether subsets of roll call votes on trade policy are correlated. A factor-analytic result allows the use of a limited number of votes for this purpose. Second, a structural model with latent variables is used to find what economic and political factors comprise these dimensions. The study yields two main findings. More than one dimension determines voting in the Senate, with the main dimension driven by economic interest, not ideology. Although two dimensions are required to fully account for House voting, one dimension dominates. That dimension is driven primarily by party. Based on reported evidence, and a growing consensus in the congressional studies literature, this finding is attributed to interest-based leadership that evolves in order to solve collective action problems faced by individual legislators.