Does more matter? Critical mass and legislative influence

Scholars are divided on whether increased group size helps or hurts political minorities. We test the concept of "critical mass" using a different kind of long-time minority: pre-realignment Republicans in the American South. In Arkansas, after a century of token status, the minority party doubled its numbers in the late 1990s, held steady through the 2000s, then surged to a super majority. This stair-stepped transformation opened a unique window to address a question thus far examined only cross-sectionally: is an outgroup's influence enhanced by an increase in numbers or does success become less likely as the majority reacts to a growing threat? We find support for the latter. As the minority expands, the likelihood their bills will be adopted, relative to majority bills, decreases markedly. The widened deficit is not, however, the consequence of diminished Republican success, but rather of a Democratic surge.