The literature on electoral reform has extensively explored the motivations of political actors in approving major changes to the electoral system and the impact of contextual variables on these political-legislative processes. However, less is known about the motivations that lead political actors to trigger episodes of electoral reform. Our research seeks to address this gap by examining legislative episodes where changes to the Portuguese electoral system were proposed. This case provides valuable insights into the dynamics of electoral reform: among the 31 countries studied by Renwick and Pilet (2016), Portugal is one of the three that currently continue to use exclusively closed lists and one of the eight that have not undergone any major electoral reform since 1990. However, there have been 12 legislative episodes of major electoral reform initiated by political parties, during which 34 proposals for changing the electoral system were presented. We test four key hypotheses: the impact of significant shifts in structures of electoral competition; the ability of major parties to gain access to office; the influence of electoral system 'pathologies' on governability; and the ideological stance of the political parties. Our study sheds light not only on the underlying motivations for proposing changes to the electoral system but also on the reasons for the frequent failure of such reforms. We specifically examine the impact of shifts in the competitive political landscape, which lead political parties to modify political institutions in order to preserve the electoral advantage gained in the recent elections. This, in turn, prompted the opposition party to engage in negotiations, presenting alternative proposals. However, the outcomes were quite different from what was expected: concerns that one party might unilaterally implement reforms, potentially harming the electoral prospects of other major parties, resulted in increased rigidity within Portugal's electoral system and the preservation of the status quo.

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