Hundreds of thousands of protesters have marched in support of Mexico City's mayor, who could be banned from the upcoming presidential election because of a legal charge against him.

The demonstrators marched down the city's main thoroughfares to the main plaza, known as the Zocalo, in complete silence. But they broke into cheers when the embattled mayor appeared on a stage and pledged to fight for the interests of the nation's poor.

Mayor Lopez Obrador, who public opinion polls say is the top contender for next year's presidential election in Mexico, enjoys broad support from poor sectors of society, all across Mexico. But his critics see him as a populist firebrand who could follow the path of Venezuela's President Hugo Chavez, who has developed close ties with Cuba's communist leader, Fidel Castro, and alienated the Venezuelan business class.

Author Elena Poniatowska, was one of the celebrities who participated in the march. She expressed concern that the political dispute between the government of President Vicente Fox and Mr Lopez Obrador could destabilize the country. "I think the situation is very dangerous. It's very polarized and people will start hating each other. Not only society people, for instance the rich classes. It's a very difficult moment for Mexico," she said.

Mayor Lopez Obrador is accused of defying a court order to stop construction of a road to a private hospital. Prosecutors want him to appear before a judge to answer these accusations. They allege that city government failed for 11 months to comply with a court order to vacate the contested land.

City authorities finally did obey the court order, but it has still not been determined whether Mayor Lopez Obrador was personally involved in any of the decision-making processes. Mr. Lopez Obrador denies any wrongdoing. Government officials say they have pursued the case against the popular mayor in an effort to show that no one is above the law. If indicted and convicted, Mr. Lopez would be prohibited from being a candidate for the leftwing Party of Democratic Revolution in next year's presidential race.