The lifebuoy being tossed to Argentina by President Trump and the Treasury secretary, Scott Bessent, is testament to the importance of the reform program now under way at Buenos Aires — and to the political peril facing President Javier Milei. Mr. Bessent’s vow that the Treasury “stands ready to do what is needed within its mandate to support Argentina” and “all options for stabilization are on the table” calmed markets, roiled by what Mr. Milei calls a “panic.”

Argentina’s fiat peso — which had been strengthening under Mr. Milei’s tenure — has in recent weeks faced pressure amid growing concerns that el presidente could be unable to move his agenda forward after losses in midterm elections. To “prevent the peso from cratering,” Bloomberg reported Friday, Argentina’s central bank, “in a desperate attempt to satisfy demand for hard currency,” intervened in the currency markets, spending more than $1 billion.

That is a sum Argentina, with but $20 billion in liquid foreign reserves, can ill afford. This recent wave of trouble was sparked by elections on September 7, when Mr. Milei’s party fared worse than anticipated against the opposition Perónists. That left-leaning bloc wants to reverse Mr. Milei’s reforms and to bring the country back to the inflationary, high-tax, statist policies that drove Argentina’s economy into the proverbial ditch.

“Markets have begun to worry that the ghost of Juan Perón is preparing a comeback,” the Wall Street Journal’s Mary Anastasia O’Grady reported on the day of the voting. Despite Mr. Milei’s success balancing the budget, largely via spending cuts, those who fed at the public trough “want to go back to the old way of doing things,” she added. Investors feared Mr. Milei would abandon the “defense of the peso and let it plunge,” Bloomberg reported.

With midterm elections looming on October 26, the concerns over the currency snowballed, prompting stocks and bonds to fall in tandem with the peso. That is the context that prompted Mr. Bessent’s move today, touting Mr. Milei’s “support for fiscal discipline and pro-growth reforms” as “necessary to break Argentina’s long history of decline.” Will the American aid, though, be enough to salvage Mr. Milei’s presidency?

More details on the bailout are expected to emerge on Tuesday after a parley between Messrs. Trump, Bessent, and Milei. The secretary said the help could include “swap lines, direct currency purchases, and purchases of U.S. dollar-denominated government debt from Treasury’s Exchange Stabilization Fund.” Yet from the libertarian vantage point of which Mr. Milei is a leading tribune, a bailout courtesy of American taxpayers is surely a disappointing turn.

Critics worry that the American aid could prove an unwise investment. The Brookings Institution’s Robin Brooks tells MarketWatch that the Treasury intervention “would involve substantial credit risk to the U.S. government” and that “it doesn’t change the underlying reality, which is the peso is substantially overvalued.” It would be a bitter irony indeed if the performance of the Argentine peso ends up proving Mr. Milei’s Achilles’ heel.

After all, Mr. Milei had called on the hustings to drop the debased peso. He said it was “a currency emitted by Argentine politicians,” and worth less than “excrement,” since it can’t be used for fertilizer. He spoke of “dollarizing” the economy, but these columns urged him to go further and restore a currency defined as a legal weight of gold. The best thing America could do for Argentina is to reform its own irredeemable electric paper ticket money.