López Castro won election as one of Mexico City's senators in the 2024 Senate election, occupying the first place on the Fuerza y Corazón por México coalition's two-name formula.[4][5]
On 29 October she resigned her membership in the PRI because of "differences with the party's current leadership", stating that she would remain in the Senate as an independent.[6] Two weeks later, she joined MORENA,[7] securing the ruling party's coalition a supermajority in the Senate.[8]