Sanchez's move is reportedly at the request of Mexican President Andres Manuel Lopez Obrador to transition back to the Senate to support his proposed reforms, according to El Universal, which cited government sources.
Sanchez, 74, was appointed to her cabinet position just months after taking her seat in the Mexican Senate, when AMLO offered her the position after his own election victory. She took an indefinite leave of absence from the upper chamber at that time. Before then, she spent 20 years as a justice on the Mexican Supreme Court.
"We express our pleasure to Dra. Olga Sanchez Cordero for her decision to rejoin as senator," Senator Ricardo Monreal said on Twitter.
AMLO's Morena party and its allies lost their supermajority in June elections, making his proposed reforms, which include constitutional changes to allow reorganizing the national guard, state utility providers, as well as financial reforms already in motion.