Argentina’s new president, Javier Milei, has been in office for just over 100 days. Since his inauguration on Dec. 10, Mr. Milei, a far-right libertarian, has been on a mission to end what he has described as “an orgy of public spending” by previous administrations that left him with “the worst inheritance” of any government in Argentina’s history.

The extreme libertarian program that Mr. Milei says will make Argentina great again — along with his unruly hair and tongue — has attracted countless comparisons to Donald Trump and won him high praise from Mr. Trump and other powerful admirers. Elon Musk indicated that Mr. Milei’s speech at the World Economic Forum in Davos, Switzerland, this year was “so hot” that it distracted from the act of sex.

But this political outsider is having a harder time convincing his fellow Argentines of his vision. A self-proclaimed “anarcho-capitalist,” Mr. Milei won the presidential race in November on promises to end Argentina’s sky-high inflation through a free-market transformation of the state. So far, he’s failed to deliver: Inflation doubled during his first month in office, though it has slowed down recently. Poverty rates have shot up; retail sales have plummeted. Mr. Milei has both faced widespread protests on the streets and hit a wall in Congress, which has twice so far rejected the plans he says will transform Argentina into “a world power once again.”

All of these headwinds have left a troubling question hanging over his new administration: Who is the real Javier Milei? Is he the economic visionary who won over voters and prompted Mr. Musk to predict that “prosperity is ahead for Argentina”? Or is he the power-hungry villain that tens of thousands of Argentines now march against on the streets, chanting “The country is not for sale!”

This much is certain: Mr. Milei is no Donald Trump. While his anti-establishment persona and inflammatory rhetoric invite easy comparisons to the former president, Mr. Milei is a product of a long South American history in which authoritarianism has been the norm and democracy the exception. Although he embraces some elements of the Trump populism flowing from North to South America — including the “Don’t Tread on Me” Gadsden flags he likes to pose with — Mr. Milei is more archetypal South American caudillo, or strongman, than Trump aspirer.

Mr. Milei, like the Venezuelan strongman Hugo Chávez, his ideological opposite, is seeking extraordinary powers in the name of saving his country. For decades, Argentina has been held up by free-market economists as one of the world’s pre-eminent examples of how progressive economic policies can lead to disaster. The argument goes that while Argentina was ruled by conservatives in the late 19th and early 20th centuries, the country was among the world’s top economies, before left-leaning governments came to power and bloated spending with unaffordable social welfare programs, generating Argentina’s chronic inflation problem. In his Dec. 10 inaugural speech, Mr. Milei waxed nostalgic for this long-ago time, boasting with undisguised exaggeration that Argentina was “the richest country in the world ” and “a beacon of light of the West.”

But Argentina was no paradise back then. A single political party clung to power through electoral fraud between 1874 and 1916. Although Argentina did become an agricultural powerhouse, the period was also marked by endemic corruption, excessive international borrowing, recurrent financial crises and empty state coffers that the government tried to fill the same way Mr. Milei wants to today — by privatizing state companies.

Argentina’s current democratic period, which started in 1983, has been the longest in its 208-year history. But the economy has proved nearly unfixable for both dictators and democratically elected leaders — left and right — since the country’s independence from Spain in 1816, marred by inflation, foreign debt defaults and various convertibility schemes.

Mr. Milei won over voters last year with the promise to end this long economic agony by attacking what he has identified as a root cause: “the aberration of social justice.” Many of his economic policies are inspired by the works of Murray Rothbard, a 20th-century American libertarian economist who befriended Holocaust deniers and whom critics accused of supporting racial segregation. Rothbard dogma were key tenets of Mr. Milei’s presidential campaign, including his “Taxation is theft” slogan and his pledge to eliminate the country’s central bank.

He blames progressive governments such as that of Cristina Fernández de Kirchner, who was in power from 2007 until 2015, for the country’s many ills. As a cure, Mr. Milei has already started dismantling Argentina’s welfare programs and removing the government from the business of education and health care.

So far, Mr. Milei does not seem averse to putting democracy on the rack as his vision of a libertarian paradise has hit political resistance. On March 14, the Senate overturned a presidential decree in which Mr. Milei conferred upon himself the power to plow ahead with cost-cutting reforms without congressional approval. (The decree remains in force, however, unless the lower house, where the president faces better odds, also strikes it down.) Last month, congressional opposition also forced him to withdraw the free-market omnibus bill that was the cornerstone of his economic plan and would have permitted him to privatize state companies and deregulate vast areas of the economy, including environmental controls and the labor market.

Mr. Milei, according to one report, said that he was going to “piss” on the governors who refused to back the economic bill and added that he could close Congress. He called the legislators who voted against the bill “parasites.”

It is an open question whether Mr. Milei has misread his voters on how far they, too, are willing to go to turn Argentina’s economy around. Mr. Milei may be testing the limits of Argentina’s on-and-off-again democracy to fulfill his dream of transforming it from a soft, populist, welfare- and social-rights-driven nation into a libertarian utopia where the fittest can realize their full potential unshackled from the weight of sharing their bounty Even if Mr. Milei’s policies do eventually tame the price of basic goods, Argentines may not embrace being denied public health policies that generations have enjoyed — or having their elected leader threaten to shut down the legislature.

Argentina is, after all, not the unmitigated economic disaster Mr. Milei and like-minded critics make it out to be. It has a diversified industrial base and is a major agricultural exporter. It has the second-highest human development index in Latin America and is its third-largest economy, with a highly educated population and a still strong, if battered, middle class that knows how to fight for its rights.

In January, soon after he took office, Mr. Milei went to Davos with a message for the world’s business people. “Let no one tell you that your ambition is immoral,” he said. “You are the true protagonists of this story and rest assured that as from today, Argentina is your staunch and unconditional ally.”

As the enthusiastic responses from Mr. Musk and others show, his message has been well received by the wealthy. But Mr. Milei will have to make an equally convincing appeal to the real protagonists in this story: the people on the streets and byways of Argentina whose patience may start wearing thin more quickly than expected if Mr. Milei does not soon slay the beast of inflation, which has seldom been tamed in our country’s long history.

If he fails, he will be remembered not as the libertarian genius that Mr. Trump and Mr. Musk make him out to be, but as just another in a long line of South American would-be caudillos who failed to deliver on their promises — and made life miserable for millions along the way.

Excerpts: New york Times