Amid the fragmentation of the opposition caucus in the Legislative Assembly, Franco defected from National Unity and joined the Social Democratic Movement, which in 2019 nominated her to accompany Oscar Ortiz as his running mate.

[6] For her part, Franco's liberal and social democratic inclinations led her to join the National Unity Front (UN), which in 2009 nominated her to represent Cochabamba's circumscription 23 as a substitute member of the Chamber of Deputies.

She topped UD's electoral list in the Cochabamba Department and was elected to hold the position, becoming one of the youngest members of an opposition caucus characterized by its high number of young female legislators.

[4][9] Franco presented three major bills throughout her parliamentary tenure, including two health-related ones, one directed at increasing government attention on persons with diabetes and one focused on procuring new treatments for cervical cancer.

In particular, she stated that cultural change needed to be legislated so as to prevent verbal harassment and cat-calling, close the gender wage gap, increase female access and permanence in education, and ensure that both boys and girls are taught the same skills.

[12] Franco's bill regulating street harassment went on to be included as part of the government's 2017 reforms to the Penal Code, but the entire legislation was ultimately abrogated due to protests over unrelated sections.

[5][13] Despite entering parliament as a partisan of UN, Franco also fostered relationships with UD's other primary component, the MDS, and, according to Deputy Jimena Costa, she was observed to have participated in the party's internal meetings from her first day in office.

[17] Franco's rapprochement with the MDS proved self-beneficial when, in July, Ortiz's running mate, Edwin Rodríguez, abruptly dropped out of the race, citing a possible dispersion of the vote in favor of the ruling party.