Political scientists generally consider that the incentive for legislators to switch parties lies in their desire to be re-elected. While some scholars attribute defection to the legislators' popularity and strong connections with their constituents which enable them to be re-elected without relying on party labels, others assert that legislators switch if they perceive that staying put might threaten their chances of re-election. In this paper, we find that the two assumptions, to some extent, contradict each other. More surprisingly, the two contradictory hypotheses cohabit under the single non-transferable vote (SNTV) system. From an analysis of the switching in the Taiwanese Legislative Yuan, the empirical evidence shows that because of fierce intraparty competition in the multimember districts, not only barely elected but also top-ranked legislators switched party affiliation in order to avoid the loss in votes or even seats to their copartisans and to maximize their chances of re-election.

In this paper, we analyze how citizens evaluate their president, especially focusing on why voters lower their evaluations at an individual-level perspective. We assert that citizens raise their evaluations of a new president when their expectations are met and lower their opinions when his or her performance disappoints them. Furthermore, the evaluations of the president are not only affected by a government's economic and diplomatic performance, but are also influenced by individual awareness of salient political issues, the contents of the news, and their own perceived influence on politics. We test the theoretical hypotheses using Taiwan's Election and Democratization Study (TEDS) panel survey data. The statistical results support our theoretical hypotheses and show that when President Ma's performance did not meet respondents’ expectations of unification and economic prosperity, the respondents updated their evaluations of Ma. In addition, it also shows that the extent of respondents’ media exposure and political efficacy are significantly associated with the change in their opinions of Ma.