Why are women strongly underrepresented in top political positions? We analyze the effect of party leaders’ gender on their ability to capitalize on political power during negotiations to form a new government after elections. We leverage the as-if random assignment of a bargaining advantage in close local elections in Spain through a regression discontinuity design and find that women are about 25 percentage points less likely than men to secure the mayor’s position when they win elections by a narrow margin, even if their parties manage to join the governing coalition anyway. This article contributes to the understanding of the role of personal characteristics in the political process and has far-reaching implications for gender equality and the quality of democratic representation.