She represents Mexico City and the fourth electoral region as a federal deputy to the LXIII Legislature of the Mexican Congress.
[1] In addition to being an alternate local deputy to the first legislature of the Legislative Assembly of the Federal District (ALDF) from 1994 to 1997, Contreras served as the secretary general of the delegation-level PRD in Tlalpan, also running its distance education center.
[1] In 2000, Contreras was tapped to direct the coordinating board of the System of Integral Women's Support Centers in the Federal District, within the National Women's Institute [es] (INMUJERES), as well as to represent the DF government on the Tlalpan Coordinating Board of Public Security and Pursuit of Justice.
In 2003, Contreras served as a legislator for the first time, representing the local 37th district in the III Legislature of the ALDF, where she presided over the Gender and Equity Commission.
[1] In 2009, she returned to the ALDF for the V Legislature after again being elected from the 37th local district, presiding over the Health and Social Assistance Commission and sitting on those dealing with Budget and Public Accounts, Human Rights, Equity and Gender, and Culture.