MEXICO CITY (AP) -- Tens of thousands of trade unionists, farmers and leftist groups marched through downtown Mexico City to protest price increases for basic foods like tortillas, the staple of Mexico's poor, and to demand a change in economic policy.
Wednesday's march represented a challenge to President Felipe Calderon's market-oriented policies. One banner read "Calderon stole the elections, and now he's stealing the tortillas!" Others waved handfuls of the flat corn disks and chanted "Tortillas si, Pan no!," a play on the initials of Calderon's National Action Party, the PAN, which also means "bread" in Spanish.
But the march, with an estimated 75,000 participants, was also a setback for his archrival, leftist leader Andres Manuel Lopez Obrador, who protest organizers prevented from speaking at the main demonstration. He held his own rally afterward.
"Mexico needs a transformation of the magnitude of the (1910-1917) Mexican Revolution," said Lopez Obrador, who also demanded wage increases, subsidies and fixed prices for basic foods, and the cancellation of a clause in trade agreements that would lift restrictions on imports of corn and beans starting in 2008.
In a news release, Calderon's office said the president shares the protesters' concerns and pledged to "continue taking all necessary actions to maintain price stability for basic goods and services, (and) punish all types of hoarding and speculation in the markets."
On Thursday, Mexican Foreign Secretary Patricia Espinosa downplayed the protests during a visit to Vienna, saying, "I wouldn't qualify it as a national crisis.
"It is of course a particularly important and problematic situation that no one expected," she added, saying Mexican economics officials were working on the matter and that Calderon had already made certain related decisions.
"We hope it will be fine in the coming weeks and months," Espinosa said.
Marchers had mixed opinions about whether the protests against rising food prices should have any connection to Lopez Obrador, who has embarked on his own quixotic campaign to deny Calderon's legitimacy following last year's presidential race Calderon won by less than 1 percentage point.
Some marchers bore placards of Lopez Obrador, the self-styled "legitimate president" of Mexico, wearing the presidential badge of office.
"El Peje is the obvious leader of the poor," said housewife Carmen Rosete, 50, calling Lopez Obrador by his nickname, a reference to a combative fish from his home state of Tabasco.
Corn farmer Servando Olivaria was among those who felt the march should be nonpartisan. "This is a spontaneous people's movement, with no political affiliation," Olivaria said. "Lopez Obrador can participate, but he should not head the march. He should not even speak about it."
The fiery former Mexico City mayor, mobilized millions in support of his allegations that the July 2 election was rigged. But since Calderon took office, Lopez Obrador's self-declared alternative government has almost faded from view.
The leftist leader tried to make a major public comeback by offering to lead the tortilla march, but he was forced to back down. He agreed to give his own speech in Mexico City's Zocalo plaza only after the organizers finish their evening rally.
The marchers are angry about tortilla prices that have doubled over the last year to roughly 10 pesos (euro0.7) per kilogram (45 cents a pound), causing hardship among the millions of poor Mexicans for whom they are a staple.
Since taking office Dec. 1, Calderon has drawn criticism for failing to control the largest spike in tortilla prices in decades. The uproar has put him in an uncomfortable position between the poor and some agribusiness industries hoping to profit off the surge in international corn prices, driven mostly by the sudden explosion of the U.S. ethanol industry.
On a weekly television show he hosts, Lopez Obrador urged his supporters to join the protest.
"We have to defend the people, because if we don't then who is going to do it?" the silvery-haired leftist asked on Tuesday.
But march organizers said they feared Lopez Obrador would take over their cause, turning it into a partisan debate that might undermine the government's willingness to respond.
"He used to have the money and influence to organize his own huge marches. Now he has to be a political opportunist and jump on someone else's train," political analyst Oscar Aguilar said. "He's burned out."
A free-market advocate, Calderon has said he does not want to return to direct price controls enforced by many former Mexican presidents.
On Jan. 18, Calderon signed an accord with business organizations to try to limit tortilla prices to 8.50 pesos (euro0.6) per kilogram (35 cents a pound). But many of the independent tortilla sellers have ignored the rate, essentially a gentlemen's agreement with no legal backing.