Argentina's Peronists soar in election to seal run-off with radical Milei

Massa had 36.6 per cent of the vote, ahead of Milei on just over 30 per cent, while conservative Patricia Bullrich was behind on 23.8 per cent with near 98 per cent of the vote counted, a result that defied pre-election polls that had predicted a libertarian win.

The surprise strength of the Peronists, despite overseeing inflation hitting triple digits for the first time since 1991, sets up an intriguing second round on Nov 19 between two polar opposite economic models for the embattled country.

Argentines had flocked to the polls on Sunday amid the country's worst economic crisis in two decades and rising anger with the traditional elite.

"I know that many of those who voted for us are the ones who are suffering the most," Massa said after the results. "Our country is experiencing a complex, difficult situation, full of challenges to face... I am not going to fail them."

Many blamed the Peronists, but Massa - a moderate - had shot back that the government's social safety nets and subsidies were key for many hard-up Argentines, including a recent stunt showing how train and bus fares could rise sharply if he lost.

That message seems to have hit home.

"Peronism is the only space that offers the possibility that the poorest of us can have basic things at our fingertips," said bricklayer Carlos Gutierrez, 61, as he went to vote on Sunday.

Milei, meanwhile, is proposing radical moves such as dollarizing the economy and has criticized major trade partners China and Brazil. He also is in favor of slashing the size of government and is anti-abortion.

To win outright on Sunday, a candidate would have needed over 45 per cent of the vote or 40 per cent and a 10-point lead.

The result, leaving things delicately poised and pushing out of the race establishment candidate Bullrich, will likely give already wobbly markets the jitters on Monday, with little clarity about the country's route forward.

"We have never had so much polarization," said 72-year-old pensioner Silvia Monto as she voted in Buenos Aires on Sunday.

Milei has pledged to "chainsaw" the economic and political status quo, luring some angry voters to his tear-it-all-down message, fed up with rising prices outstripping salaries.

"He is the only one who understands the situation in the country and understands how to save it," said Buenos Aires student Nicolas Mercado, 22.

Milei, in a defiant speech after the result, said he would fight on to win in the second round next month.

"We are faced with the most important election of the last 100 years," he said. "If we work together we can win, if we work together we can recover our country."

Election authorities said turnout was around 74 per cent, up from the August primaries, but considerably lower than the 81 per cent participation at the last election and the lowest general election turnout since the 1983 return to democracy.

Whoever emerges victorious will have to deal with an economy on life support: central bank reserves are empty, recession is expected after a major drought, and a $44 billion program with the International Monetary Fund (IMF) is wobbling.

Silvana Dezilio, 37, a housewife in Buenos Aires province, said it was hard to see a positive outcome whoever won.