She occupied the posts of local deputy, federal deputy and federal senator for Tabasco, and in Andrés Manuel López Obrador's government she was the Administrator General of Fiscal Audit of the Servicio de Administración Tributaria (SAT; "Tax Administration Service").
[3] In the PRD, López Hernández occupied the posts of national and state counsellor in Tabasco; in 2000 she was nominated and elected federal deputy for Tabasco District 4 to the LVIII Legislature of the Mexican Congress, an office lasting from this year until 2003, and in which she held positions as Secretary of the Treasury and Public Credit Commission and as Member of both the Commission for Vigilance of the Federation's Higher Auditing and the Committee of the Centre of Public Finance Studies, as well as being a member of the Friendship With India Group and of the Latin American Parliament's (PARLATINO) Emerging Economies Commission.
She did not serve out her full term, instead asking for permanent leave beginning on 1 March 2012 to stand for the second time as a candidate for the PRD for a seat in the Congress of Tabasco in the state elections to be held that same year,[7] which saw her elected by proportional representation to the LXI Tabasco State Legislature, which would end in 2015.
In that year, she forsook her PRD militancy and accepted a candidacy from the National Action Party (Partido Acción Nacional, PAN) and the Ecologist Green Party of Mexico (Partido Verde Ecologista de México, PVEM) for the municipal presidency (mayoralty) of Centro in the 2015 state elections;[8] she did not win, however, losing to Gerardo Gaudiano Rovirosa, the PRD and New Alliance candidate, and ending up in third place among voters' preferences.
[9] López Hernández died on 5 June 2024 at the age of 56, only three days after being elected for the second time as a senator for the state of Tabasco.