Runner-up presidential candidate Andres Manuel Lopez Obrador called on hundreds of thousands of supporters at a rally Sunday to set up encampments in the central square and along miles of the capital's most famous boulevard until a federal tribunal orders a recount of the July 2 election.
The popular leftist alleges that a conspiracy of government and big business steered the election to conservative Felipe Calderon, the unofficial winner by a margin of less than a percentage point.
"From the beginning we had signs of our victory and now, 28 days after the election, we have the certainty," said Lopez Obrador, standing in front of a two-story-high banner with the slogan of his campaign to force a recount: Vote by vote.
"Without a doubt," he said to cheers, "we have won the presidency."
Hours after the rally in downtown's central square, or Zocalo, tents began springing up on two major avenues through the capital. One of them, the 14-lane Paseo de la Reforma, was partially blocked for miles by 8 p.m.
Lopez Obrador promised to live among the protesters in 47 encampments that sprouted Sunday along the heavily traveled Avenida Juarez and Paseo de la Reforma, a Parisian-style boulevard of ritzy hotels, the U.S. Embassy, government offices, and roundabouts that circle statues of the Roman goddess Diana, Christopher Columbus and Mexico's Angel of Independence.
"All the camps must have discipline, respect and cleanliness," Lopez Obrador told the crowd, which approved the idea in a show of hands. "Let's take care of the gardens, the historic monuments. No graffiti on public spaces and avoid provocation. All of our acts will follow the idea of peaceful civil resistance, with no violence."
Protesters have long set up camps on the Zocalo. Last year, hundreds of farmers and their wives pitched tents on park strips along the Reforma. They stood naked for days under the Angel of Independence statue, hoping to shame government officials into concessions in a land dispute.
But no such encampments -- in Spanish called plantones -- compare with the scale ordered by Lopez Obrador. He called for representatives of each of the country's 31 states, as well as the 16 districts that make up Mexico City, to pitch camps along a 4.6-mile stretch of the city center.
"Frankly, I believe they'll end up taking over the streets because of the number of people -- they just won't fit," said Gerardo Fernandez Norona, a spokesman for Lopez Obrador's Democratic Revolution Party.
Few expect Mexico City Mayor Alejandro Encinas, a member of Lopez Obrador's party, to take action against the protesters. Lopez Obrador stepped down as mayor a year ago to run for president and has broad political support here, among both citizens and local government.
"We're going to do everything in our power to maintain the city's daily life," Encinas said.
Calderon, meanwhile, spent Sunday afternoon telling the seven judges of the Federal Electoral Tribunal that the election was won fair and square.
Lopez Obrador lawyers made their case to the judges Saturday.
"We won the election," said Calderon after the closed-door hearing. "The question is now whether we resolve the differences among Mexicans with mobilizations and pressure or with reason and the law."
Calderon's camp does not believe Lopez Obrador has a legal basis to ask the tribunal to order a recount.
Although the election showed some statistical oddities -- such as polling stations in strong Lopez Obrador districts tallying more votes for the Senate race than for president -- the ballot box discrepancies appear to hint at error rather than fraud.
Only proof, not suspicion, can compel the tribunal to reopen ballot boxes, argued Calderon, who edged Lopez Obrador by 244,000 votes out of 41.8 million cast, according to unofficial returns.
The elections tribunal has until Sept. 6 to declare a winner. If it does not, Mexico's new Congress, which takes office Dec. 1, would have to appoint an interim president and set a new election.
Calderon had campaigned as Mexico's "jobs president" and promised to continue the free-market policies of President Vicente Fox, from the same conservative National Action Party.
He served briefly as Fox's energy secretary until they had a falling out over Calderon's presidential ambitions.
Lopez Obrador's campaign slogan was "For the good of all, the poor first," and he promised financial relief to senior citizens, single mothers and the unemployed.
The election split Mexico between those seeking to join the country's transition to the free market and those who felt squeezed out of the game. Lopez Obrador voters largely disapproved of Fox, who by law can serve only a single six-year term that ends in December.
Sunday's rally, which city officials said drew 2 million people, had a party atmosphere, with food, music and souvenirs. Buses brought families from around the country.
But many also were angry. When asked, they scowled over low wages, the lousy prospects in their town and the idea, pushed by their leader, that a cadre of the rich and powerful may have decided the election for them.
"We can't get office jobs so we have to resort to selling on the street: cigarettes, popsicles. That's the only job for the poor," said Manuel Ortiz Garcia, 62. "Fox talks about 'A better Mexico,' but only for his family and his millionaire friends."
Carlos Martinez and Cecilia Sanchez in The Times' Mexico City Bureau contributed to this report.