MEXICO CITY, April 24 – A capital typically clogged with traffic was thronged Sunday by hundreds of thousands of people who marched into the main plaza to protest a government effort against Mayor Andrés Manuel López Obrador that threatens to force him out of next year’s presidential elections.
The police estimated that more than one million people participated in the march. Aides to the mayor estimated that there were 750,000 people. Several political observers described it as the biggest in the country’s recent history.
After two weeks of heated political discourse and confusing legal maneuvers, the march was not the first to denounce the government’s campaign against the mayor. But it was a dramatic illustration of seemingly growing support for Mr. López Obrador and disappointment in President Vicente Fox.
The demonstrators were of all ages and walks of life. Some came from the southernmost corners of Mexico. There were men in business suits and women in traditional Indian clothes. And while some said they had been longtime supporters of the mayor, others said that even though they were not likely to vote for him they thought the government’s campaign against him was unfair.
Unlike most other demonstrations, there was no real disorder or rowdiness. And people covered their mouths with hospital masks and marched without chanting.
“Our silence says everything,” read many of the banners that floated above the crowds. Others depicted Mr. Fox as a traitor.
Rocio Jiménez González, a 26-year-old lawyer, wore a banner that urged Mexico to follow the example being set in Ecuador.
“They got rid of their president,” she said. “It’s time for Mexico to do the same.
“I am here to defend the democracy of my country, or what little there is of it,” she added. “We cannot allow a few people in power to control the will of the majority by decree.”
Mr. Fox did not comment on the demonstration on Sunday. His government was been widely criticized after Congress voted April 7 to lift Mr. López Obrador’s immunity so he could stand trial in a minor land dispute.
Under most interpretations of Mexican law, Mr. López Obrador, of the leftist Party of the Democratic Revolution, cannot run for office or be put on the ballot until after a trial, which could take more than a year.
The situation has plunged Mr. Fox’s party and his cabinet into open conflict.
Meanwhile, Mr. López Obrador has reveled in the moment. He announced that he would return to work as normal on Monday. And while he urged the government to back away from its case against him, he also sent his opponents a message of conciliation.
“I hope our adversaries will rectify this situation,” he said, “that they will back away from their animosity and disqualifications.
“We are never going to bet on destroying our adversaries,” he said. “The task of transforming the country requires tolerance, agreement and, above all, no wasting time on political vengeance.”
Antonio Betancourt contributed reporting for this article.