Microphone in hand and standing atop the sound truck, the raspy-voiced protest leader jabbed his finger into the air shouting for the ouster of Brazilian President Dilma Rousseff, igniting wild cheers from the crowd below him.

"What Lula and Dilma have done shouldn't just result in their being banned from politics. It should result in them being in jail!" Kim Kataguiri yelled, denouncing Rousseff and her predecessor, Luiz Inacio Lula da Silva.

The March 15 demonstration was the largest Sao Paulo had seen in more than three decades, since 1984 protests demanding democratic elections after a long dictatorship.

But more surprising than the crowd of over 200,000, according to the Datafolha polling and statistics agency, was the fact it was being led by Kataguiri, a skinny, 19-year-old college dropout, and other young Brazilian activists inspired by libertarianism and conservative free-market ideals.

The grandson of Japanese immigrants, Kataguiri is a social media star whose quirky videos skewer Rousseff and the ruling party's social welfare policies. His ascent as a protest figure has been rapid. Two years ago, when protests erupted across Brazil over corruption and poor public services, Kataguiri was a high schooler who avoided the unrest.

Today, he is the public face of the Free Brazil Movement, a growing force that is more focused than the 2013 unrest that expressed a wide range of middle-class anger. Brazil's new wave of protests are seen as a right-leaning movement clearly channeled against Rousseff and her Workers' Party.

A widening kickback scandal at Petrobras, the state oil company, is one of several complaints undermining the administration. Kataguiri and others are striking a chord with Brazilians fed up with soaring inflation, a high and growing tax burden, and those who blame government intervention for hobbling Brazil's economy, which grew just 0.1 percent last year and is expected to shrink in 2015.

"We are starting to see an agenda that is very politically driven and clearly against the federal government and President Dilma," said Carlos Melo, a political scientist at the Sao Paulo-based Insper business school. Compared to 2013, "these protests are presenting very different visions."

Kataguiri says he had a political awakening two years ago when he began questioning a classmate's position that a popular cash transfer program applauded by many experts around the globe was responsible for the expansion of Brazil's middle class and for lifting millions of citizens from poverty during the last decade.

He believed the credit instead should go to the country's commodities boom. "That's what has helped the poor," he said.

He began posting satiric videos to YouTube, which gained a following. He joined two digital media collectives and produced more clips. Along the way, Kataguiri read the works of free-market economists Milton Friedman and Ludwig Von Mises.

His videos, in which he and his cohorts often don wacky costumes and dress up as political figures such as Fidel Castro, caught the eye of Danilo Gentili, a top late-night TV comedian who fiercely lampoons the government. The comedian asked Kataguiri and other young, anti-Rousseff producers and designers to help create a sketch before the October presidential runoff vote, which saw Rousseff narrowly beat her more conservative, market-friendly opponent.

Today, Kataguiri and the Free Brazil Movement team work from an office that has a tech-startup feel, with two brown leather couches and a clothes rack holding costumes used in their videos. Tequila and mescal bottles sit along a bookshelf holding Rand Paul's "The Tea Party Goes to Washington" and Russell Kirk's "The Politics of Prudence."

Kataguiri and others in the group believe the best remedy for Brazil's corruption is the expansion of free-market views and making the government smaller and more fiscally responsible — following classic tenets of American conservatism.

Some media in Brazil have railed against the young libertarians, accusing them of receiving money from right-wing groups in the U.S. — specifically the billionaire energy mogul Koch brothers, strong supporters of American conservative causes.

Kataguiri and Renan Santos, the other co-founder of the Free Brazil Movement, deny this, saying the U.S. influence is strictly ideological. Their campaigns are low-cost and easily sustained by private donations and fund-raising.

Some members of the movement have brought home techniques from the Atlas Leadership Academy, a training program run by the Atlas Network, a Washington-based organization promoting free-market policies around the world. Affiliated groups in other Brazilian cities where protests took place on March 15 are connected to Students for Liberty, a U.S. youth group allied with the conservative Cato Institute think tank, which is supported by the Koch brothers.

On a recent evening at the Free Brazil Movement headquarters, Kataguiri and others worked feverishly on their Macs, creating Internet memes ridiculing Rousseff, and pushing out news stories, videos, and information about the upcoming protest to their Facebook followers, more than 105,000 and growing.

Some members were boxing up orders of T-shirts and stickers with the "#ForaPT" hashtag — "#Workers' Party Out" — which they say is their only source of funds besides donations — while Santos loudly strummed on an acoustic guitar.

The group is working to meet with influential congressmen it hopes may be persuaded to start impeachment proceedings against Rousseff — something that even Congressional opposition leaders are not publicly backing, since there is no evidence linking the president to the Petrobras scandal.

The administration, however, may be sliding toward trouble. Melo, the political scientist, said the Free Brazil Movement and other groups are tapping into the widespread discontent and turning more Brazilians against Rousseff, whose approval rating fell to 13 percent in March, an all-time low.

"She is in a dangerous, tough spot," Melo said. "Much of the population has lost faith in regards to the future and her ability to govern. These groups are making her look more vulnerable."

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