Huge crowds have rallied in Mexico's capital, protesting against proposed changes to the electoral authority ahead of June's presidential elections.
The Mexico City government said some 90,000 people turned out in the city's Zocalo Square. The rally organisers said the figure was much higher.
The opposition accuses President Andrés Manuel López Obrador of trying to weaken the National Electoral Institute - an autonomous, non-partisan body.
He says the INE is biased and corrupt.
Since his victory in the 2018 presidential elections, Mr López Obrador has been pushing for a reform of the INE, which he says will save taxpayers $150m (£119m) a year by drastically reducing the agency's staff.
Sunday's demonstration in the capital's historic square is the latest such protest in Mexico in recent years.
"We do not want our autonomous institutions to be attacked, we want to defend our democracy, we want the INE... to be independent, and we want our president to keep his hands off the election," demonstrator Diana Arnaiz was quoted as saying by the AFP news agency.
Maria de Jesus Torres, who also attended the rally, said: "We are millions of Mexicans who are against this government and I am coming out for my children and grandchildren."
Mr López Obrador is not able to seek re-election because Mexican presidents are limited to a single six-year term.
He is supporting former Mexico City Mayor Claudia Sheinbaum, who is currently leading the opinion polls.
Ms Sheinbaum, a member of his ruling Morena party, on Sunday officially entered the race by submitting her registration papers.