INCUMBENT VULNERABILITY AND CHALLENGER EMERGENCE IN SENATE ELECTIONS

We examine challenger emergence in Senate elections by looking at the 1992 campaign in depth. We develop improved measures of incumbent vuln erability using data from the 1988 and 1990 NES Senate Election Studie s. These measures are used to test the hypothesis that higher-quality challengers are more likely to challenge vulnerable incumbents. We fin d generally weak relationships between our incumbent vulnerability mea sures and challenger quality. Instead, challenger quality scores incre ase with the size of tile pool of potential high-quality challengers.