Argentina’s libertarian president, Javier Milei, has caused a political firestorm by promoting an unknown cryptocurrency token that shot up in value after his endorsement and then swiftly cratered.

In a post on social media on Friday night, Mr. Milei said that the coin, called $LIBRA, would stimulate the economy and help small businesses grow. While the sudden attention gave the token an initial boost, the huge gains were erased as fear quickly spread that the coin was a scam.

Mr. Milei deleted his social media post five hours later and attempted to distance himself from the venture.

“I was not familiar with the details of the project,” he wrote on X, “and after having informed myself I decided not to continue disseminating it (that is why I deleted the tweet).”

But Mr. Milei rapidly came under fire for his role in pushing people toward a risky investment. His dalliance with crypto also prompted comparisons with President Trump, who launched a memecoin, $Trump, last month. That token surged for a while and then crashed.

A center-left coalition that opposes Mr. Milei’s libertarian government called his crypto foray “a scandal without precedent.” Another political bloc said it was seeking to create a commission in Congress to investigate what occurred.

Former President Cristina Fernández de Kirchner, Mr. Milei’s main political nemesis, said that “thousands” who had trusted him lost millions of dollars in all, “while many made fortunes due to privileged information.”

Mr. Milei’s promotion of $LIBRA was only the latest in a series of moves he has made in parallel with Mr. Trump. Mr. Milei withdrew Argentina from the World Health Organization earlier this month, and his staff has said that the government is examining whether to withdraw from the Paris climate accord.

The coin promoted by Mr. Milei was presented as an investment tool that would be good for the country.

In his initial post on X, he said that $LIBRA — a name that carries echoes of his political party, La Libertad Avanza — would “incentivize the growth of the Argentine economy, funding small companies and Argentine ventures.”

“Liberal Argentina is growing!!!” Mr. Milei added, saying that “the world wants to invest in Argentina.”

Not long after, a community note on X warned users to be cautious with $LIBRA. It urged people to “verify before interacting with the project” because of behavior consistent “with a rug pull.” That term refers to scam offerings by developers who create a crypto token, attract investors and then suddenly disappear, withdrawing all their money.

Shortly after midnight, Mr. Milei deleted his post. He later said that he had no personal ties to the crypto token. He lashed out at his critics, who he said were trying to score political points.

“I want to say that every day they confirm how lowly politicians are,” he said.