本文旨在探討選舉並立制與半總統制影響憲政運作的因果途徑。在第三波民主化後，隨著以並立制為國會選制的國家數目增加，而使並立制受到廣泛關注。不過，在涉及並立制制度效果的相關研究中，制度結構之差異卻往往被忽略或少有討論。本文運用三個解釋變項，分別是半總統制憲政體制－包含總統議會制與總理總統制、選舉時程，以及總統所屬政黨或同盟議員選舉制度，以評估總統對政黨的實質影響力。透過亞美尼亞、烏克蘭與喬治亞的案例比較，本文發現，在總統對政黨實質影響力較強（最強、次強）的情況下，有利於形成偏向總統中心的憲政運作。當總統對政黨實質影響力較弱（最弱、次弱）時，則使偏向總統中心的憲政運作難以確立，然而，這並不必然導致偏向以總理與國會為中心的憲政運作。彙整本文論點，憲政體制與選舉制度對於憲政運作之影響，尚須考量制度結構差異，以及總統與國會藉由選舉時程而相互牽動等因素。

This article examines the causal pathways through which the parallel voting system and semi-presidential system affects constitutional operations. Following the third wave of democratization, the parallel voting system has garnered increased attention due to the rising number of countries adopting it. However, in studies addressing the effects of the parallel voting system, variations in institutional structures are often overlooked or scarcely discussed. This paper introduces three explanatory variables: the type of semi-presidential system (either presidential-parliamentary or premier-presidential), the electoral schedule, and the primary method for selecting members of the president's party (or alliance). These variables are used to assess the substantive influence of the president on the party. Through a comparative analysis of Armenia, Ukraine, and Georgia, this study suggests that when the president's substantive influence over the party is stronger (whether strongest or second strongest), it tends to favor a president-centric constitutional operation. Conversely, when the president's influence is weaker (either weakest or second weakest), it may challenge the establishment of such an operation. However, this does not necessarily lead to a prime minister and parliament-centric constitutional operation. To conclude, the influence of the constitutional and electoral systems on constitutional operations must account for differences in institutional structures and the mutual influence between the president and parliament during electoral schedule.

半總統制、並立制、憲政運作、總統、總統權力

semi-presidential system, parallel voting system, constitutional operation, president, the power of the president