This article analyzes the incidence of the size of the constituency at the municipal councils in the electoral achievements of three heterogeneous parties with national influence recently incorporated into the political game. These parties went to the polls for the fist time in 2015 for subnational elections in Colombia: The Center Democratic Movement (CD), the Alternative Indigenous and Social Movement (MAIS) and the Patriotic Union (UP). The results confirmed the electoral rule that, depending on the voting volume of each political organization, the larger constituencies, these parties are more likely to locate their candidates in the councils, because the percentage of votes required to access a seat at the council decreases. Although this is the constant, there are some exceptions, indicating the need to consider other factors of the electoral system, such as, the political campaign, the parties themselves, and the context, in order to explain the achievements of new political parties in municipal political corporations.