Explaining Party Cohesion in Congress: The Case of Shared Policy Attitudes

Partisanship has often been noted as one of the most conspicuous factors in legislative voting in the U.S. Congress. This paper attempts to trace party voting to shared policy goals. After the mean attitudes of congressmen belonging to the same party were ascertained for a number of policy domains, the effect of mean party attitudes on roll-call voting was estimated by regression analysis, taking into account the deviation of individual congressmen from their respective mean party attitudes. The results demonstrate that in all three policy domains examined, i.e., social welfare, civil rights, and foreign policy, shared party attitudes leave a strong imprint on individual roll-call decisions. The voting decisions of congressmen, in fact, are found to owe more to the shared party attitudes than to their own individual attitudes. The paper also explores the communication process through which shared policy attitudes are translated within Congress into partisan roll-call votes and points to a way of reconciling the “predispositional” and the “interactional” approach to legislative decision making.