Social divisions, party support, and the changes in the Thai party system since 2001

This article investigates the interactions of socioeconomic characteristics and electoral outcomes at the constituency level to demonstrate the change in the Thai party system since 2001. Probing the effects of the agricultural population and income inequality on electoral outcomes in the proportional representation (PR) tier, this article finds that the Thai Rak Thai Party (TRT) and the Democrat Party (DP) attracted voters with opposite social standings. While voters residing in the provinces with substantial agrarian populations tended to vote more for the TRT than the DP, constituencies with highly unequal income distribution were more likely to be DP supporters. The findings provide evidence against alternative explanations, including regionalism and support for a charismatic leader, for the TRT’s consecutive victories. Due to the convergence between social divisions and party support, the Thai party system has become stable and strong enough to resist short-term interventions, implying that the future electoral outcomes will likely be similar