We develop a model that nests previous explanations for women under-representation in positions of power. Focusing on democratic electoral dynamics, our framework delineates the three types of mechanisms that may be at play: consumer demand, candidate supply, and internal party dynamics beyond electoral markets. We use Spain's Equality Law, requiring a 40 percent female quota in electoral lists, to test the alternative theories. The law was enacted by the social-democratic party after the surprise parliamentary electoral results following the Madrid terrorist bombings, and was therefore completely unexpected by regional political machines. The law only applied to towns with populations above 5000, so we can use a treatment-control, before-and-after discontinuity design to learn about the impact of female politicians in local elections. Our evidence is most consistent with the existence of entrenched male-dominated political machines capturing influential power positions within the parties.