MP behavior in mixed-member electoral systems

•I develop a model for MP behavior in mixed-member electoral systems.•It considers joint effects of dual candidacy in district and on party list.•Only MPs in competitive districts not secured by party list focus on district.•Empirical investigation shows that model is superior to mandate divide.

Previous research has argued that representatives in mixed-member electoral systems adjust their behavior to the mode of their election, the so-called mandate divide. MPs elected in single-member districts focus on their district, whereas those elected through closed party lists focus on their party. Yet this ignores that candidates in mixed-member systems can run in a district and on their party's list concurrently. This paper presents a model of how the prospects of re-election in the district and through the party list affect the relationship between voters, candidates, and parties. It is shown that the dual candidacy option results in candidates focusing on their party in most instances. The model is applied to a novel data set on the allocation of federal road construction projects in Germany.