MEXICO CITY (AP) — Mexico’s President Claudia Sheinbaum on Thursday downplayed the defeat of a constitutional reform proposal in the Congress, her first major legislative setback since taking office, saying there was a “Plan B” to make changes to the electoral system.

With defections from some members of the smaller allied Green and Workers parties, Sheinbaum’s Morena party did not have the supermajority to pass the proposal in the Chamber of Deputies on Wednesday evening. Some of the proposed changes, which Sheinbaum’s party has framed as budget austerity measures, were viewed as reducing the power of smaller parties.

Sheinbaum, who took office in 2024, warned Thursday that voters will judge whether politicians from those other parties had complied with their promise to support her administration’s agenda.

One of the main sticking points was that the proposal to do away with a system that lets parties fill some seats in Congress on the basis of proportional representation. That was designed to give smaller parties some seats in Congress, based on their national vote percentage, even if they couldn’t win individual congressional district races.

Sheinbaum had pushed to have all members of Congress elected by voters.

The proposal also wanted to reduce the cost of elections by 25%, including funds for the National Electoral Institute and money given to all parties. Experts said the changes could endanger the running of Mexico’s elections and make the governing party stronger.

Georgina de la Fuente, a political science professor at the Tecnológico de Monterrey University, said that what the vote shows “is that the small parties are not going to give their unconditional support (to Morena), they are not going to put their survival at risk.”

Sheinbaum said she would provide more details on what “Plan B” is on Monday, but added that the intent remains the same: “to continue reducing privileges.”