MEXICO CITY — Mexico’s leftist ruling coalition was on track to lose its absolute majority in Congress following midterm elections on Sunday, putting brakes on President Andrés Manuel López Obrador’s ambitious plans to overhaul the country’s economy and society.
The ruling Morena party was expected to hold between 190 and 202 seats in Mexico’s lower house of Congress, a decline of up to 60 lawmakers, according to preliminary results released Monday by the country’s electoral board.
Although Morena, together with allies, will still be the dominant force in the 500-seat legislature, the coalition is expected to fall well short of the two-thirds majority required to change the Constitution and push for Mr. López Obrador’s reform agenda.
“It’s a powerful reversal,” said Carlos Bravo Regidor, a political analyst and professor at the Center for Economic Research and Teaching in Mexico City.
In particular, the results will make it more difficult for Mr. López Obrador to advance his flagship plan to return Mexico’s energy sector to state control. Despite the president’s enduring popularity, especially among the poor, the results appear to show the limits of his popular mandate to change the nation under a bold program of reforms he has billed Mexico’s “Fourth Transformation.”
In a silver lining for the government, Mr. López Obrador’s coalition was expected to make major gains in the hundreds of state and local electoral offices also contested at the polls, deepening Morena’s national reach and cementing the dominance of a party that was founded less than 10 years ago.
The Mexican peso rallied nearly 1 percent in early Monday trading, one of the best performances among emerging market currencies, suggesting the business sector was reacting positively to new checks on Mr. López Obrador’s power.
The main opposition parties performed better than expected at the polls, after deciding to put aside major ideological differences and confront Mr. López Obrador in a coalition. The pro-business National Action Party will be the biggest opposition force in Congress, with 106 to 117 seats. A pro-business candidate also led the preliminary results in the governor’s race for the state of Nuevo León, Mexico’s economic powerhouse.