On Challenger Strength In Japanese Lower House Elections

This research tests the hypothesis that Japanese Lower House (multimember) districts with more open seats attract more strong challengers. Lower House incumbents are reelected at higher percentage rates than challengers are elected. Using data for the 10 most recent elections to the Lower House (1963-90), measures appropriate to the medium-sized district, single-entry ballot electoral system were constructed for the proportion of open seats and the effective number of strong challengers in each district. Analysis shows that strong challengers enter district races in proportion to the opportunities presented by open seats. Differences in the electoral strength of candidates for the Japanese House of Representatives are readily apparent. Incumbents enjoy obvious electoral advantages over challengers. Success in previous campaigns, experience in office, and higher visibility make incumbents formidable opponents. There are also clear differences in the strength of challenger candidacies. Some challengers offer serious electoral competition and threaten to displace the weakest incumbents. Other challengers enter races with little expectation of gaining office. Defeated independent candidates, Communist party candidates, and minor party candidates are numerous in every general election to the Lower House of the Diet. Districts with open seats-that is, multimember districts with fewer incumbent candidates than seats-would appear to offer challengers crucial opportunities for gaining office. This study addresses the question of whether, in fact, Lower House districts with open seats attract more strong challengers. There are good reasons for believing that strong challengers decide to enter races by calculating the likelihood of being elected, rather than by heeding the behest of party or faction. Since the Diet is a parliamentary body, one might expect competition on the basis of party and ideology; however, Diet elections clearly exhibit some of the