Expectations about election outcomes shape voter behavior, yet little research has examined how expectations regarding the post-election formateur influence voting decisions. This study examines the conditions under which voters engage in formateur optimization – strategically supporting parties with a realistic chance of forming the government rather than their most preferred party. We argue that while formateur uncertainty plays a key role, its effect depends on voters’ preferences regarding their most preferred party and their preferred formateur. Using modules 1–5 of the Comparative Study of Electoral Systems (CSES) and German pre-election surveys (1998–2021), we find that formateur optimization is more likely in tightly contested elections. However, our results also show that voters’ preferences moderate the effect of formateur uncertainty: formateur optimization remains low even under high uncertainty when voters strongly favor a non-formateur party over the formateur’s party. Furthermore, we find that voters who expect their preferred formateur candidate to lose behave similarly to those uncertain about the outcome – and still engage in formateur optimization. These findings highlight the interplay between expectations and preferences in shaping voting decisions in coalition systems, offering new insights into voter calculations in multiparty democracies.
