Mexico City ? More than 100,000 defiant supporters of leftist presidential candidate Andres Manuel Lopez Obrador massed Saturday in a bid to overturn his narrow election defeat with protests that threatened to widen Mexico’s regional and class divisions.

Lopez Obrador told the huge crowd he would present allegations of fraud to the nation’s electoral court today and request that every one of more than 41 million votes be recounted, to expose what he called wrongdoing.

“We are going to ask that they clean up the elections. We are going to ask that they count all the votes – vote-by-vote, poll-by-poll,” Lopez Obrador said to wide applause.

He called for marches that would converge on Mexico City in another rally July 16, provoking groans of disappointment when he told demonstrators not to block highways.

“This has been and goes on being a peaceful movement,” Lopez Obrador said. “We are not going to fall for any provocations.”

The show of defiance suggested just how difficult it will be for apparent victor Felipe Calderon to unify Mexicans, many of whom believe the nation has yet to overcome decades of institutional corruption and fraud.

European Union election observers have said they had found no major irregularities.

But the ruling party’s Calderon can’t be declared president-elect until the electoral court weighs allegations of fraud or unfair campaign practices. It has until Sept. 6 to declare a winner.

Election officials say Calderon beat Lopez Obrador by less than 244,000 votes out of a total of 41 million ballots – or a margin of about 0.6 percent.

Most of Lopez Obrador’s supporters come from poor southern states while conservative Felipe Calderon’s strength is in Mexico’s industrialized north.

Calderon, who says the vote was clean, has already declared himself the winner and has received congratulatory phone calls from President Bush, Canadian Prime Minister Stephen Harper, Spanish Prime Minister Jose Luis Rodriguez Zapatero and Colombian President Alvaro Uribe.