Electoral Systems and Legislators' Constituency Effort: The Mediating Effect of Electoral Vulnerability

In so far as legislators value re-election, electoral institutions are said to shape their strategic behavior. Yet, the empirical evidence linking legislators? behavior to electoral institutions is weak at best. Previous studies, we argue, have either ignored or misspecified how legislators? vulnerability to electoral defeat mediates the expected effect of electoral institutions. To test this argument, we develop and operationalize a new comparative measure of electoral vulnerability which we combine with new individual-level data on legislators? constituency effort in 14 (mostly European) countries. Our data demonstrate that the effect of electoral institutions on constituency effort is different dependent on legislators? electoral precariousness. In party-centered systems, district magnitude?s negative effect grows weaker among those most vulnerable. In candidate-centered systems, by contrast, district magnitude?s positive effect grows even stronger among those most vulnerable. The results suggest the need to revisit studies focusing exclusively on the impact of institutions on legislators? constituency-oriented behavior.