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Mexico's main leftist candidate said Sunday he was digging in for a long battle in the disputed presidential race, dismissing a ruling against his demands for a full recount and calling for a huge demonstration in front of the country's top electoral court.

Speaking to tens of thousands of followers in Mexico City's main Zocalo plaza, Andres Manuel Lopez Obrador asked his followers to remain indefinitely in their sprawling protest camps that for the past week have brought much of the capital's normally thriving center to a halt. The blockades have snarled traffic, costing the city an estimated $23 million a day in lost commerce.

Lopez Obrador said he would not drop his demand for a recount of every vote in the July 2 election, despite the Federal Electoral Tribunal's decision Saturday in favor of a partial recount. Electoral officials will begin sifting through ballots from 9 percent of the nation's 130,000 polling places Wednesday, wrapping up their work by the weekend.

CountryWatch: Mexico

Before Lopez Obrador's speech, protesters chanted in favor of seizing Mexico City's airport and some suggested taking over Congress, moves that would almost certainly trigger confrontations. Security has been increased at both facilities.

While the leftist candidate did not say whether he would eventually approve such tactics, he did promise "new actions, new measures of civil resistance" and asked his followers "to prepare ourselves for a struggle that may last longer."

"Even if I wind up alone, if I have the conviction that I am fighting for a just cause, I would continue, stubbornly," Lopez Obrador said.

Lopez Obrador's supporters were enraged Saturday when the tribunal ruled against their demands for a ballot-by-ballot recount that they argue will show the leftist was the true winner of the election.

"We don't want anybody except him as president," said Maria Acosta, 52, a Mexico City housewife. "We are not going to allow this fraud. ... We will take this as far as is necessary."

An official count found that conservative Felipe Calderon of President Vicente Fox's National Action Party has an advantage of less than 0.6 percent, or about 240,000 votes.

The tribunal has until Sept. 6 to declare a president-elect or annul the vote. The partial recount could swing the vote in favor of Lopez Obrador, if electoral officials — supervised by judges — find evidence of widespread problems.

Mexico's Federal Electoral Institute, an autonomous agency often credited for bringing democracy to Mexico, has said the election was clean and fair, defending the work of thousands of volunteer poll workers. Most international observers have said they failed to note major problems.

Lopez Obrador has called electoral officials criminals and even alleged that some of his own party officials took bribes to plot against him. He asked his supporters to gather in front of the tribunal Monday evening to demand the court "correct" its decision, likely snarling traffic on yet another main Mexico City street.

He accused the ruling party and its followers of "promoting racism and classism" and trying to maintain their hold on power, recalling 71 years of one-party rule that ended with Fox's historic victory in 2000.

Leaders of other parties supporting Lopez Obrador called on protesters to follow Fox and demonstrate at every one of the president's public events.

Since the election, Lopez Obrador has accused Fox of influencing the vote and called him a "traitor to democracy."

Fox has tried to stay out of the debate. On Friday, when a Lopez Obrador protester interrupted his speech, he told his audience: "Leave him alone, and let him enjoy this country's freedom of expression."

The Mexico City government, controlled by Lopez Obrador's Democratic Revolution Party, has protected protest camps that have blocked the elegant Reforma Avenue and the Zocalo.

But on Sunday, police chief Joel Ortega indicated his patience was wearing thin, telling a news conference that "everything has a limit."

The election has divided the nation along class and social lines. Lopez Obrador has promised to govern for the poor, while Calderon has the backing of the nation's growing middle classes and ruling elite.

"The powerful ... have fed classism, racism and intolerance," Lopez Obrador said Sunday, adding: "They have made — although they hypocritically try to hide it — the color of someone's skin, and contempt for the poor and those under them, their main cause."

Early Sunday, hundreds of Mexicans celebrated a Mass at Mexico City's Basilica, praying for unity, reconciliation and peace.