A defeated leftist presidential candidate declared himself "legitimate president" of Mexico, vowing to fight the president-elect taking office in less than two weeks.

Andres Manuel Lopez Obrador donned a presidential sash in a symbolic swearing-in before tens of thousands of his supporters jammed into Mexico City's Zocalo plaza, who cheered as he held up two fingers in a "V" for victory.

Without naming president-elect Felipe Calderon, whom he accuses of usurping the July 2 election, Lopez Obrador, 53, laid out the road ahead for his government in a 40-minute speech. Observers said he was preparing the way for another presidential bid in 2012.

"I commit myself to protecting the rights and property of the Mexican people. If I do not, let the nation hold me accountable," he said in the mock swearing-in.

Lopez Obrador called for "the start of construction of a new republic against a neo-fascist oligarchy" and announced the formation of a "parallel government" to "protect the rights of the people, the patrimony and the national sovereignty."

"It is an honor to be the legitimate president of Mexico," he said, wearing a replica of the green, white and red presidential sash.

"We will fight on for our ideals," he said.

Followers of his Democratic Revolutionary Party (PRD) have threatened to disrupt the December 1 inauguration of Calderon, 44, who succeeds President Vicente Fox.

Lopez Obrador alleges electoral fraud in the July 2 election, which he lost by a 0.56 percentage point. But a protracted recount and eventually the country's highest electoral authority confirmed Calderon's razor-thin victory.

And international observers declared the polling fair but Lopez Obrador insists his loss was due to fraud by the National Action Party (PAN), which supports Calderon and Fox.

"We will not give the right wing free rein to do whatever it wants," he told followers Saturday at a massive rally in northern Mexico. "We are going to fight them."

Lopez Obrador timed the launch of his opposition government to coincide with the November 20 anniversary of the 1910 Mexican Revolution, when revolutionaries Francisco Madero, Emiliano Zapata and Pancho Villa took up arms against conservatives to found modern-day Mexico.

Lopez Obrador led weeks of protest in a tent city that paralyzed downtown Mexico City after the July 2 election.

A former Mexico City mayor known for bolstering his populist agenda with mass demonstrations and fiery speeches, Lopez Obrador said his opposition government plans to hound Calderon's administration.

Even before Calderon's inauguration, Lopez Obrador blamed him for rises in the prices of gasoline and milk, announced last week.

In particular, he said he would keep a close watch for any move by the Calderon administration to privatize the state-run oil industry.

"We'll gather thousands, millions of people to prevent that from happening," he said.

For some political analysts, the opposition leader's intentions are clear.

"It's a way of preparing his candidacy for the next (2012 presidential) election and so keep himself in the limelight," said Oscar Camacho, who co-authored a book about the leftist politician's failed bid for the presidency.

Lopez Obrador could be fined if the presidential sash used at Monday's ceremony is deemed too similar to the real sash bearing the red, white and green colors of the Mexican flag which by law only the president is allowed to wear.

Despite his following in Mexico City, Lopez Obrador's popularity has eroded, polls published Monday showed.

According to the newspaper Milenio, "he has become the politician with the worst image in the country, with 57 percent negative ratings."

At the beginning of the presidential campaign in February, 63 percent had a positive image of the ex-mayor, while 19 percent did not, it said.

Copyright © 2006 Agence France Presse

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