Buenos Aires (Argentina) (AFP) - Argentina’s budget-slashing leader Javier Milei pulled off a stunning win in Sunday’s midterm elections, boosting the flagging reform agenda of the US-backed right-winger.

Milei’s La Libertad Avanza (LLA) party rebounded from a series of setbacks to win 40.84 percent of the votes cast for members of Congress, official results based on over 90 percent of votes counted showed.

The center-left Peronist movement, which had been riding high after winning last month’s Buenos Aires provincial elections, trailed with 31.64 percent, the partial results showed.

The result strengthens Milei’s hand as he moves ahead with his campaign to downsize the state and deregulate the economy – although he will still need to forge alliances in Congress with the center-right to pass legislation.

At LLA’s election night party, hundreds of Milei’s supporters celebrated the results with cheers, hugs, chants and even some tears.

“I’m very happy and excited; I didn’t expect such a large number,” Facundo Campos, a 38-year-old marketing consultant, told AFP.

“God bless Argentina,” Milei’s spokesman Manuel Adorni wrote as a reaction on X.

The elections were the first national test of Milei’s support since he won office two years ago on a promise to revive the long-ailing Argentine economy through a series of painful reforms.

Half of the seats in the Chamber of Deputies and one-third of the Senate seats were up for grabs on Sunday.

The run-up to the election was marked by a run on the national currency, the peso, that forced Milei to seek a bailout from US President Donald Trump, a close ally.

Washington promised an unprecedented $40 billion package of aid, but the assistance came with a warning from Trump to Argentines that he would not “be generous” if Sunday’s election did not go Milei’s way.

- Low turnout -

Ahead of the election, several Milei voters had expressed disappointment with his leadership, particularly over corruption scandals involving members of his inner circle.

But they also voiced continued opposition to the Peronist movement, which governed Argentina for much of its post-war history but has been widely accused of corruption and mismanagement.

At 67.9 percent, turnout was the lowest in a national election in over 40 years, reflecting widespread disillusionment with the political class.

The most surprising results were in Buenos Aires province, where LLA clawed its way back from defeat in last month’s local elections to run neck-and-neck with the Peronists.

Adriana Cotoneo, a 69-year-old pensioner voting in Buenos Aires, told AFP she backed Milei’s party “not because I believe it’s the best option, but because I’m clear about who I want to be gone.”

Former TV pundit Milei, 55, has cut tens of thousands of public sector jobs, frozen public works, cut spending on health, education and pensions and led a major deregulation drive since taking office in December 2023.

His reforms were blamed for initially plunging millions of Argentines deeper into poverty. They did however slow inflation by two-thirds – to the relief of many – although at the expense of faltering economic growth, consumption and manufacturing.

Investors began dumping the Argentine peso last month amid concerns over the economy and support for Milei, but Trump stepped in to shore up his closest Latin American ally.

Ahead of the election, expectations were high that the government could depreciate or devalue the peso, widely seen as too strong.

Questioned about the possibility on Sunday, Economy Minister Luis Caputo replied: “No.”

“Monday is just another day, nothing changes to the economic program or the band system,” he said, referring to the peso-dollar exchange rate band set by the government in April.