Pollster Parametria forecast Sheinbaum winning a landslide 56% of the vote, according to their exit polls, with opposition candidate Xochitl Galvez on 30%.

Four other exit polls also said Sheinbaum was set to win.

Provisional results will trickle in over coming hours. Galvez has not conceded and told her supporters to be patient for the official results.

A victory for Sheinbaum would represent a major step for Mexico, a country known for its macho culture. The winner is set to begin a six-year term on Oct. 1. "I never imagined that one day I would vote for a woman," 87-year-old Edelmira Montiel, a Sheinbaum supporter in Mexico's smallest state Tlaxcala, said earlier on Sunday.