2004年参院選における自民党からの離反と小泉評価

抄録

In the 2004 House of Councilors (HC) election, we observed a nation-wide swing of votes which caused a major setback for the ruling Liberal Democratic Party (LDP). This was a drastic swing compared with the 2001 HC election. In order to make clear the factors underlying this swing, this study analyzes data from the Asahi Shinbun- University of Tokyo joint survey. Our hypothesis is that the decline of the LDP in the 2004 election was caused by the waning of Koizumi's “coattail effect”.
The results of the analysis show that the swing was brought about by the voters' negative evaluation of Koizumi cabinet or Koizumi himself, the party, and other issues such as constitutional reform or the pension system. The study also indicates that there is an evaluation gap between the performances of the LDP and Prime Minister Koizumi, and that the positive evaluation of the latter did not contribute to votes to the former. Moreover, votes for the LDP under the Proportional Representation system in the 2004 HC election included supporters for the so-called “Teikou Seiryoku-resistance force” within the LDP.
The leadership of Koizumi is often characterized as a variation of populism, with his mass-appealing attitude on the media and his tendency to reduce political issues down to oversimplified, dualistic categories. However, the results of this study suggest that many voters made their voting choices based on the evaluation of the Koizumi government rather than being blindly affected by populist tactics.