Coalition of Extremes: Ideology and Partisanship in the United States Congress, 1947-1998.

This paper examines a phenomenon that is almost invisible in the political science literature on Congress but quite common in actual congressional behavior - roll calls in which a coalition of left and right ideological extremes votes against a coalition of the centrists or moderates. By a conservative measurement strategy, such votes occur about 20 percent of the time in the House and somewhat more often in the Senate. This paper develops an empirical measure of the incidence of votes of a Coalition of the Extremes, applies it to more than 26,000 roll call votes from 1947 to 1998, and investigates factors that make such voting more or less likely. The general conclusion is that the Coalition of Extremes voting pattern shows that ideology, as distinct from partisanship, is a more important force in Congress than is generally recognized. [ABSTRACT FROM AUTHOR]