MEXICO CITY – Angelica Cruz, who sells fruit on Mexico City’s streets, speaks with near-religious fervor when she talks about her devotion to Andres Manuel Lopez Obrador, the leftist former mayor of Mexico City, who’s challenging his apparent narrow loss in Mexico’s July 2 presidential race.

“He is our only hope,” the 30-year-old mother of three said. “He helps the people because he belongs to the people. He has a humble, honest soul.”

For days, thousands of people, Cruz among them, have been keeping a vigil in Mexico City’s main square, the Zocalo, in anticipation of a rally planned for Sunday in support of Lopez Obrador’s claims that the election was stolen from him. His opponent, conservative Felipe Calderon, was declared the winner by about half a percentage point.

The willingness of people such as Cruz to turn out has kept Lopez Obrador’s candidacy alive, in spite of two ballot counts that show him losing and open skepticism about the evidence he’s offered of wrongdoing.

Poor, disenchanted and ardently committed, they’ve lent his challenge the feel of a religious crusade and given him a media bully pulpit as he prepares his legal challenge before a special elections court. They’ve also provided an air of crisis to a raucous national debate about the substance of his fraud allegations. The court has until Sept. 6 to resolve them and proclaim a victor.

“His moral superiority is his ace in the hole,” said John Ross, an election observer and student of Mexican politics. “In 40 years I’ve been here, I’ve never seen a politician with this kind of connection to his people. It’s tangible. You can see it.”

Some political observers say his followers’ zeal is matched only by that of Lopez Obrador himself, who once lived among the Chontal Indians of his native Tabasco state and sees himself as a champion of the poor.

To his critics, and not only those in Calderon’s National Action Party, that passion stems from a paranoid demagogue who’s willing to exploit Mexicans’ skepticism of the ruling classes, who have traditionally had their way with the country’s electoral system.

“He sees himself not only representing the poor but incarnating their struggles,” said author George W. Grayson, a College of William and Mary government professor who monitored the election. “He really has messianic tendencies. For him, it’s good against evil.”

“They are thieves,” Cruz said in a sweeping indictment of Calderon and Mexico’s election officials, who so far have upheld his victory by a margin of fewer than 244,000 votes.

At a post-election protest outside the Federal Election Institute, Grayson said, Lopez Obrador backers played some of the same music that was heard during the last papal visit to Mexico. Banners of the Virgin of Guadalupe, Mexico’s patron saint, sometimes are interspersed among political signs demanding a total “vote for vote” recount.

No one knows how many people to expect for Sunday’s rally. A similar gathering last weekend attracted perhaps as many as 300,000. From Baja California to Chiapas, tens of thousands set off Wednesday toward the capital, many in colorful caravans waving their campaign’s yellow flags, along with banners declaring “No to fraud.”

Some observers worry that Lopez Obrador won’t be able to tame the passions he’s unleashed on the streets.

“He’s playing with fire,” said Jorge Chabat, a professor of politics and economics in Mexico City. “At some point he might not be able to control his people. He has promised them a lot.”

Most notably, besides promising a better deal for Mexico’s poor, Lopez Obrador has promised them victory.

His campaign’s central logo has an uplifting, almost beatific tone. “Smile,” he implores his followers. “We’re going to win.”

Speaking with reporters Thursday, Lopez Obrador said his election challenge was bigger than his Party of the Democratic Revolution and him. “It is,” he said, “for the sake of democracy itself.”

In the Zocalo, Cruz and other followers compare him to national hero Benito Juarez. References to Cuban revolutionary Che Guevara are also common in the open-mike speeches that have occupied the marchers this week.

Lopez Obrador adviser Jesus Ortega said the party had every intention of maintaining calm at Sunday’s rally, which he called the “the second act” of last weekend’s protests.

But some early arrivals, such as Cruz, say they’ll remain defiant. “The people have to rise up,” she said. “If we lose there will be a war.”

For the moment, most onlookers are dismissing the prospect of significant civil unrest. But as more protesters join what’s turned into a five-day occupation of the nation’s central square, the fever pitch has risen.

“They are very passionate,” Chabat said. “They are very angry, because they’ve had a bad situation for years. It’s still not rational. But who said politics was rational?”

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