MEXICO CITY—Mexico’s ruling party declared Claudia Sheinbaum the winner of the presidential election by a “large margin” after polls closed on Sunday, putting her on course to be the country’s first female president.
Pollster Parametria forecast Ms. Sheinbaum winning a landslide 56 percent of the vote, according to their exit polls, with opposition candidate Xochitl Galvez on 30 percent.
Four other exit polls also said Ms. Sheinbaum was set to win.
Provisional results will trickle in over coming hours. Ms. Galvez has not conceded and told her supporters to be patient for the official results.
The winner is set to begin a six-year term on Oct. 1.
Ms. Sheinbaum’s ruling MORENA party has also declared its candidate the winner of the Mexico City mayorship race, one of the country’s most important races, though the opposition has disputed that and claims its own nominee won the contest.
Sunday’s vote was marred by the killing of two people at polling stations in Puebla state, adding to multiple attacks that have made Mexico’s largest-ever elections also the most violent in its modern history. Some 38 candidates were killed, with the violence stoking concerns about the threat of warring drug cartels to democracy.
Security fears dominated the concerns of many voters at the polls and Ms. Sheinbaum will be tasked with confronting organized crime.
Pre-election polls indicated that MORENA and its allies will likely fall short of securing a two-thirds majority in Congress. That would make it more difficult for Ms. Sheinbaum to push constitutional reforms past opposition parties.
Among the new president’s challenges will be tense negotiations with the United States over the huge flows of U.S.-bound migrants crossing Mexico and security cooperation over drug trafficking at a time when the U.S. fentanyl epidemic rages.
At home, the next president will be tasked with addressing electricity and water shortages and luring manufacturers to relocate as part of the nearshoring trend, in which companies move supply chains closer to their main markets.
The election winner also will have to wrestle with what to do with Pemex, the state oil giant that has seen production decline for two decades and is drowning in debt.
Ms. Sheinbaum has promised to expand welfare programs, though Mexico has a large deficit this year and sluggish GDP growth of just 1.5 percent expected by the central bank next year.
