Supporters of Mexico's leftist presidential candidate brought rush-hour traffic to a crawl Monday, causing the stock market to drop and forcing office workers dressed in business suits and high heels to hike for miles to work.

The sprawling tent cities in the financial heart of the Mexican capital were another sign that Andres Manuel Lopez Obrador and his supporters won't accept anything less than victory from the top electoral court.

The tribunal is weighing allegations that fraud gave ruling party candidate Felipe Calderon a slight advantage in the July 2 election. It has until Sept. 6 to declare a president-elect or annul the elections.

Lopez Obrador is demanding a vote-for-vote recount, and has vowed to block the city center until the Federal Electoral Tribunal rules on his request.

CountryWatch: Mexico

Mexico's stock market opened lower Monday, a sign the protests were making investors nervous.

"We'll stay here for as long as it takes, but we're not going to let them impose a president on us," said farmer Anacleto Garcia Martinez, 53, as he warmed his coffee on a wood-burning brazier set up beneath a tarp strung from the wrought-iron gate leading to Chapultepec Park.

With his broad mustache and a blanket hung over his shoulders, he resembled his ancestors, farmers-turned-soldiers in Mexico's 1910 revolution.

"We've got revolutionary blood," said fellow farmer Angel Campirano, 49, of the city's rural Milpa Alta district. "Farmers are being forced to sell off their land, and we are defending the land."

But modern Mexico — which now depends more on commerce, services and manufacturing than on agriculture — has little patience with such sentiments.

Salesman Alejandro Lara, 33, walked two miles up Mexico City's swank Reforma Avenue, blocked by protesters, before he began shouting.

"I'm either going to have to get up at 5 a.m. every day, or ask for vacations," Lara said angrily. "It's too bad, because I supported Lopez Obrador. But now, after this, I wouldn't want to have him governing us. He scares me."

Lara was among hundreds of office workers who passed protesters blaring salsa music and playing soccer in streets blocked by barrels, scrap wood, ropes and lawn chairs.

Cesar Nava, a spokesman for Calderon, called on Mayor Alejandro Encinas to reopen the streets to traffic, contending Lopez Obrador's leftist Democratic Revolution Party — of which Encinas is a member — had 'kidnapped' the city.

"What they're doing is kidnapping Mexico City," Nava told reporters. "We see that as an unacceptable, partisan act and absolutely contemptuous of democracy."

"The mayor up to now has been an accomplice to the flagrant breaking of the law. We hope he changes his behavior and starts acting like a mayor," Nava said.

In Washington, State Department spokesman Sean McCormack expressed confidence Mexican authorities would resolve the dispute.

"They have declared a winner. There are provisions for appeals. We have full confidence in the ability of these Mexican institutions to deal with this kind of situation," McCormack said.

There was no estimate of the economic damage from the protest. Some businesses were closed, and a few tourists could be seen struggling with their luggage on blockaded streets.

Marches and protest camps are common in Mexico City, a megalopolis of 20 million people, but Sunday's rally and resulting tent cities were on a scale that hasn't been seen in recent Mexican history.

Democratic Revolution spokesman Gerardo Fernandez defended the protests, saying: "They are absolutely peaceful and absolutely legal. We are not violating anyone's rights."

Encinas said Monday his government wouldn't forcibly remove the protesters. President Vicente Fox's spokesman, Ruben Aguilar, said federal authorities also won't step in, unless the city requests their help.

"The organizers of these demonstrations and marches have said they will be peaceful and respect the rights of others," Aguilar said. "We hope they keep their word."

Lopez Obrador is known for his ability to mobilize millions. Last year, he led marches that successfully blocked an attempt to impeach him as Mexico City mayor, a move that would have kept him from running for president.

Calderon, who has an advantage of about 240,000 votes, or 0.6 percent of the official count, argues the election was fair and has condemned the street protests as "senseless."

"The question is whether we Mexicans are going to resolve our differences with pressure tactics and marches, or with reason and by law," Calderon said Sunday after testifying before the tribunal's seven judges.

Protesters included grandmothers, politicians and housewives. Many were drawn by Lopez Obrador's promises to govern for the poor.

"A lot of us are not poor. A lot of us are doing this out of a desire for justice and equality," said Rebeca Garcia Guzman, a retired health care worker and middle-class mother.

While Lopez Obrador has called on demonstrators to remain calm, the protesters say things could turn violent.

"This is the start, and it is going to generate more, higher-impact protest actions," said Carlos Reyes Gamiz, a city councilman who spent the night in a tent. "Positions in this conflict are going to harden."

That already appeared to be happening. Maricarmen Montano, a secretary, stood outside a subway stop and tried to figure out how to get to work. She was already two hours late and desperate.

"What did we do to deserve this? This is shameful," Montano said.

Montano isn't wealthy. But like many Mexicans, she views herself as part of an emerging middle class and fears a return to the era of open confrontation between rich and poor.

"He comes from a low-class neighborhood, and it shows," Montano said of Lopez Obrador. "If he's upset, he should go to the courts. This kind of thing shouldn't be settled in the streets."