Sheinbaum, the favored successor of outgoing President Andrés Manuel López Obrador, vowed to continue on the direction set by the populist leftist leader. But the cool-tempered scientist offers a sharp contrast in style — and a break with Mexico's male-dominated political culture.

"I promise that I am not going to let you down," Sheinbaum said, greeting supports in Mexico City's colonial-era main plaza, the Zocalo.

The National Electoral Institute's president said Sheinbaum had between 58.3% and 60.7% of the vote, while opposition candidate Xóchitl Gálvez had between 26.6% and 28.6% and Jorge Álvarez Máynez had between 9.9% and 10.8% of the vote. Sheinbaum's Morena party was also projected to hold its majorities in both chambers of Congress.

The climate scientist and former Mexico City mayor said that her two competitors had called her and conceded her victory.

The official preliminary count put Sheinbaum 28 points ahead of Gálvez with nearly 50% of polling places reporting.

The fact that the two leading candidates were women had left little doubt that Mexico would make history Sunday.

"As I have said on other occasions, I do not arrive alone," Sheinbaum said shortly after her victory was confirmed. "We all arrived, with our heroines who gave us our homeland, with our mothers, our daughters and our granddaughters."

Sheinbaum will also be the first person from a Jewish background to lead the overwhelmingly Catholic country.

She will start her six-year term Oct. 1. Mexico's constitution does not allow reelection.