Do Unions Punish Democrats? Free-Trade Votes and Labor PAC Contributions, 1999–2012

This article examines whether labor unions punish incumbent Democrats who vote for free-trade bills in Congress. We theorize that punishment is a risky strategy for interest groups that prefer one party over the other. Therefore, interest groups must be substantially affected by decline in party support to punish. Consistent with our theory, we find important differences between public- and private-sector unions in their willingness to punish. Although public-sector unions articulate opposition to free trade, they do not follow through with either deterrence (withholding contributions to send a signal) or incapacitation (withholding contributions to replace the wayward candidate with a more supportive one). Private-sector unions, specifically unions that organize trade-vulnerable industrial workers, do attempt to punish Democrats via deterrence. The estimated deterrence effect is a 6 percent reduction in contributions. This study improves on previous studies by modeling punishment across several congressional sessions and multiple trade votes. The results reveal new insights into labor's approach to declining protectionism among congressional Democrats.