The party at the heart of Mexico City's protest

To its critics, the massive ongoing occupation of downtown Mexico City, led by presidential candidate Andrés Manuel López Obrador, is a hotbed of anarchy and a breeding ground for violence in the wake of the country's disputed July 2 election.

Yet a visitor could easily mistake this historic moment in Mexico's budding multiparty democracy for, well, a night at the summer fair.

Along more than five miles of the blockade, circus-size tents cover couples dancing salsa and merengue. Children whirl on kiddy rides. A comedian draws laughs from a crowd eating corn-on-the-cob and drinking cola. There are any number of one-man guitar shows, folding chairs provided.

The demonstration was called two weeks ago by the leftist leader, who trails conservative Felipe Calderón by little more than half a percentage point, to demand a full vote-by-vote recount to clear up doubts of fraud. An electoral court denied the request, wrapping up a review of 9 percent of polling places Sunday, a move many expect won't alter the results. Obrador told a crowd Sunday to be prepared to resist as long as necessary: "We could be here for years if the circumstances merit it."

His tactics have drawn ire from commuters and businesses, who've lost many hours and millions of dollars. But the atmosphere under the tarps stands in contrast to angry rhetoric on both sides and claims that Mexico's nascent democracy could buckle under strain. In fact it's a sign, experts say, of democracy in action.

"Latin American politics today is a bit of a carnival," says Riordan Roett, head of Latin American studies at Johns Hopkins School of Advanced International Studies. "This is something [the people] could not have practiced in the same way 15 or 20 years ago ... What we are seeing is a massification of politics."

Far from a violent protest, the sit-in, or plantón as it's known in Spanish, is a family affair, with music, rides, and art classes. It's a free daycamp of sorts. Chess, basketball, and soccer tournaments – on turf grass set up on the street – have been organized. "Parents can leave their kids here if they have to work," says Victor Maldonado Garcia as he watches over kids quietly coloring photos of Obrador in an art "workshop" with markers and pencils.

Like any good festival, the plantón has offered opportunities for novice artists. Take David Chino, who's always taken photos as a hobby but never dreamed of having his own exhibit. Now he basks in the applause that erupts as a sheet of paper is lifted to reveal his photos of women leaders from his hometown. "I feel happy," says Mr. Chino, "that my point of view can be expressed for so many."

Mexico's 2006 election, the first since the demise of 71 years of one-party rule in 2000, is often compared to the 1988 elections, when fraud kept the ruling party in power. Then angry protests erupted – but to no avail.

Obrador "has the privilege of organizing nonviolent resistance because he does not have to risk an aggressive response," says John Ackerman, an expert on Mexican electoral law at the National Autonomous University of Mexico. "It was more tense then. There was a lot less hope that the people could be successful." On Sunday Obrador called for major rallies in September, including one to determine the future of his movement.

Obrador has even begun comparing his nonviolent struggle to that of Martin Luther King Jr. If the court, which must certify a winner by Sept. 6, declares Mr. Calderón the winner, Mr. Roett says Obrador has an important political choice to make. "You can't say, 'I respect the rules only if I win,' " he says.

For now, visitors stroll along car-free streets and inspect facades and statues that are typically just a blur from inside a cab. The foot-traffic is a boon for capitalists, who sell everything from books to flan in plastic cups.

Most activities carry a political tone. On children's rides, posters call President Fox a traitor. Protesters leave their tents to hear speeches by Obrador, who invokes legendary leaders, such as Benito Juárez, the nation's first indigenous president, in his struggle for the underserved. Such comparisons seem overblown to some, but like many supporters, Julio César López says Obrador is the only modern leader who cares about the poor. He's begun wiring together wooden crates for a sculpture to tower above the tarps. When it's done it will feature a two-headed bust, made from bamboo and newspaper, of Obrador's profile emerging from that of Benito Juárez.

• Ms. Llana is Latin America correspondent for the Monitor and USA Today.