Abstract
Although party voting in the U.S. Senate has been affected by long-term and short-term factors, models in previous research have ignored this distinction. The author employs a relatively new tool, error correction modeling, to measure the long- and short-term effects of internal and external factors on party voting in the U.S. Senate. The results show that party voting for both major parties is a long-term equilibrium relationship with ratification of the 17th Amendment and that external factors are much more important than internal ones for explaining changes in levels of party voting.