Buenos Aires, May 19 (AP) What was once one the bastion of the center-right in Argentina fell on Sunday to the radical libertarian party of President Javier Milei, a dramatic result that could help the leader's chances in crucial midterm elections later this year as voters across the country's capital abandoned the main conservative party.

Milei's top candidate and official spokesperson, Manuel Adorni, swept to victory in the Buenos Aires elections, securing over 30% of the ballots and crushing the center-right party of former President Mauricio Macri in its stronghold.

Milei's La Libertad Avanza party, or LLA, said it racked up twice as many votes Sunday as it did in the last local election, in 2023.

As a brassy Argentine rock anthem blared at the post-election rally, Milei burst onto the stage, bouncing and pumping his arms to whip up the crowd.

“Today is a pivotal day for the ideas of freedom,” he bellowed, reveling in the cheers of supporters.

The upset marked a bruising defeat for Macri's PRO (Republican Proposal) party, which has governed Buenos Aires uninterrupted for the past 18 years. The PRO candidate, Silvia Lospennato, came in third with 15.9% of the vote.

“The results are not as expected,” Lospennato acknowledged. “We have a lot of work ahead of us." Argentina's left-leaning populist Peronist party, which has governed the country for much of the past two decades, came second, scraping over 27% in a city where they normally fall short, a sign of how the splintered right-wing has benefited the opposition.

“The Peronist party is far from dead with this result,” said Juan Cruz Díaz, a political analyst who runs the Cefeidas Group, a consultancy in Buenos Aires.

But the main takeaway from Sunday's vote, he said, “is the fight for dominance in the center-right and the strong victory over the PRO party.” Some 2.5 million people were eligible to vote in Sunday's election, in which half of the 60 legislative seats were up for grabs. Turnout was far lower than usual, hovering around 53%.

Widely seen as a power struggle between far-right Milei and center-right Macri, this local race reflected the shifts that hard-right factions have pulled off around the world, from Europe to the United States, squeezing the political center.

“It turned into a crucial battle for the political leadership,” said Ignacio Labaqui, a senior analyst at research group Medley Global Advisors.

The result cements Milei's party as Argentina's main alternative to the left-leaning Peronist movement championed by former President Cristina Fernández de Kirchner, who governed for eight years after succeeding her husband in 2007. Under her watch, Argentina became notorious for its unbridled state spending and massive budget deficits.

“What this election yielded is that society understands we're the best way to end Kirchnerism for good, which was nothing but a tragedy for Argentina,” Adorni said in his victory speech, referring to the political movement of former President Kirchner.

The win also strengthens Milei's hand ahead of midterm elections in October, a high-stakes vote in which he hopes to expand his party's tiny congressional minority to complete his economic and institutional overhaul of Argentina.

A former TV pundit known for his angry rants against Argentina's political class, Milei founded LLA just four years ago, drawing a motley crew of political novices into his anti-establishment agenda.

With his party holding just 15% of seats in the lower house and 10% in the Senate, the president was forced to strike deals with Macri, the scion of a wealthy family who governed from 2015-2019, in order to push his harsh austerity measures through Congress.

Macri supplied Milei's new government with key ministers, brought him a conservative base and helped him secure the support of critical political brokers and powerful governors.

But their uneasy alliance faltered over various disagreements, such as Milei's recent effort to bypass Congress to install a contentious judge accused of corruption on the Supreme Court.

Macri has increasingly criticized Milei's bellicose approach to politics and what he called his “lack of respect” for Argentina's institutions.

“Putting the economy in order is not enough. We must strengthen institutions, be predictable and regain respect for one another,” Macri told supporters last week.

The Milei-Macri rivalry turned ugly on Sunday as Macri's party filed a complaint with the Buenos Aires Electoral Tribunal over a widely shared artificial intelligence-generated deepfake of Macri announcing that his candidate was dropping out of the race and urging voters to back Milei's candidate instead.

While the origin of the false video was unclear, Macri blamed Milei's supporters for “breaking all the rules." In response, the city's electoral court said it had ordered Elon Musk's social network X to take down the manipulated video.

X did not immediately respond to a request for comment. (AP) AS AS