NEWSMAKER-Argentine rock-singing libertarian Javier Milei shakes up presidential election race

By Anna-Catherine Brigida and Maximilian Heath

BUENOS AIRES, Aug 14 (Reuters) - Argentina's presidential election race has an unpredictable X factor: Javier Milei, a fiery and wild-haired libertarian who wears leather jackets, belts out rock songs to his supporters, calling his political opponents "thieves."

The 52-year-old economist, whose brash showmanship has shades of former U.S. president Donald Trump, won the largest share of the vote in open primary elections on Sunday, shaking up the race to become the country's next president.

He has shot from relative obscurity a few years ago to now having a real shot at the South American country's presidency, with his combative, rock-style rallies appealing to voters angry at 116% inflation and rising poverty.

He has pledged to "blow up" the political status quo, shutter the central bank, dollarize the economy, and massively shrink the state - ideas that have resonated with many voters, especially the young, after years of economic decline.

"Milei is a phenomenon," said Benjamin Gedan, director of the Latin America and Argentina programs at Washington-based think-tank the Wilson Center, adding that his rise had rattled the two main political blocs.

"His plague-on-both-your-houses message resonates among voters fed up with traditional political parties. And there are legions of these voters."

Milei's strong performance has turned the Oct. 22 election into a three-way scrap, challenging the governing Peronist coalition and the main conservative opposition grouping Together for Change, who came in close behind him in the primaries.

Whether or not he wins, his party will have significant sway in Congress and he will have a powerful platform for his unorthodox economic views, likely pressuring any government in power to shift to the right.

In his closing campaign event last week, Milei rocked into an arena, singing and surrounded by cheering fans. He has railed against the "caste" of the political elite who he calls "robbers" taking money out of voters' pockets.

"We are facing the end of the caste model," he said after the primary election results. "Today we have stood up to say enough to the model of decadence. Today we took the first step for the reconstruction of Argentina."

His jubilant supporters chanted: "We can feel it. Milei President!".

A former small-time rock musician and athlete, Milei opposes abortion and supports gun rights. He has criticized worker-friendly labor laws as a "cancer," said the state is the "basis of all problems," and praised U.S. gangster Al Capone as a hero.

Milei's rise reflects a wider regional trend in recent years that has seen Latin American politicians from outside mainstream parties rise to prominence with pledges to break up the status quo.

"People are fed up with politicians," said Adriano Gabriel Zoccola, a 31-year-old lawyer from Buenos Aires who supports Milei because of his economic proposals and plans to slash government spending and cut the number of ministries.

"If Argentina is going to have real change, something completely different has to emerge. I think that Javier is the right person," added Zoccola, who said he had previously voted for Together for Change.

Opponents say Milei's proposals are unrealistic. That includes the plan to dollarize the economy, something most Argentines oppose despite rapid depreciation of the peso currency and high inflation. A dollar-peso peg introduced for similar reasons in the 1990s brought short-term benefits but ended in an ugly devaluation.

Diana Mondino, an economist and adviser to Milei who is running for Congress for his party, said his reputation for being unyielding was the reason many people didn't like him but was also the very thing that made him successful.

"He's not willing to negotiate," said Mondino. "He's willing to say: 'What do we need to get things done?' It might hurt, but it will get done." (Reporting by Anna-Catherine Brigida and Maximilian Heath; Editing by Adam Jourdan and Rosalba O'Brien)