BUENOS AIRES, Argentina - Voters in Argentina head to the polls Sunday in a presidential runoff election that will determine whether South America's second-largest economy will take a rightward shift.

Populist Javier Milei, an upstart candidate who got his start as a television talking head, has frequently been compared to former U.S. President Donald Trump. He faces Economy Minister Sergio Massa of the Peronist party, which has been a leading force in Argentine politics for decades.

On Massa's watch, inflation has soared to more than 140% and poverty has increased. Milei, a self-described anarcho-capitalist, proposes to slash the size of the state and rein in inflation, while Massa has warned people about the negative impacts of such policies.

The highly polarizing election is forcing many to decide which of the two they consider to be the least bad option.

'Whatever happens in this election will be incredible,' said Lucas Romero, director of local political consultancy Synopsis. 'It would be incredible for Massa to win in this economic context or for Milei to win facing a candidate as professional as Massa.'

Voting stations open at 8 a.m. (1100 GMT) and close 10 hours later. Voting is conducted with paper ballots, making the count unpredictable, but initial results were expected around three hours after polls close.

Milei went from blasting the country's 'political caste' on TV to winning a lawmaker seat two years ago. The economist's screeds resonated widely with Argentines angered by their struggle to make ends meet, particularly young men.

'Money covers less and less each day. I'm a qualified individual, and my salary isn't enough for anything,' Esteban Medina, a 26-year-old physical therapist from Ezeiza, on the outskirts of Buenos Aires, told The Associated Press on the sidelines of a Milei rally earlier this week.

Massa, as one of the most prominent figures in a deeply unpopular administration, was once seen as having little chance of victory. But he managed to mobilize the networks of his Peronist party and clinched a decisive first-place finish in the first round of voting.

A banner reading in Spanish: 'No to the privatization of Argentine trains, no to Milei' hangs at the Retiro train station in Buenos Aires, Argentina, Nov. 18, 2023.

His campaign has cautioned Argentines that his libertarian opponent's plan to eliminate key ministries and otherwise sharply curtail the state would threaten public services, including health and education, and welfare programs many rely on. Massa has also drawn attention to his opponent's often aggressive rhetoric and has openly questioned his mental acuity; ahead of the first round, Milei sometimes carried a revving chainsaw at rallies.

Massa's 'only chance to win this election when people want change ... is to make this election a referendum on whether Milei is fit to be president or not,' said Ana Iparraguirre, partner at pollster GBAO Strategies.

Milei has accused Massa and his allies of running a 'campaign of fear' and he has walked back some of his most controversial proposals, such as loosening gun control. In his final campaign ad, Milei looks at the camera and assures voters he has no plans to privatize education or health care.

Most pre-election polls, which have been notoriously wrong at every step of this year's campaign, show a statistical tie between the two candidates. Voters for first-round candidates who didn't make the runoff will be key. Patricia Bullrich, who placed third, has endorsed Milei.

Javier Rojas, a 36-year-old pediatrician who voted for Bullrich in October, told The Associated Press he's leaning toward Milei, then added: 'Well, to be honest, it's more of a vote against the other side than anything else.'

Underscoring the bitter division this campaign has brought to the fore, Milei received both jeers and cheers on Friday night at the legendary Colon Theater in Buenos Aires.

The vote takes place amid Milei's allegations of possible electoral fraud, reminiscent of those from Trump and former Brazilian President Jair Bolsonaro. Without providing evidence, Milei claimed that the first round of the presidential election was plagued by irregularities that affected the result. Experts say such irregularities cannot swing an election, and that his assertions are partly aimed at firing up his base and motivating his supporters to become monitors of voting stations.

Such claims spread widely on social media and, at Milei's rally in Ezeiza earlier this week, all those interviewed told the AP they were concerned about the integrity of the vote.

'You don't need to show statistically significant errors - if you draw enough attention to one problem in one polling station which likely doesn't affect the results in any meaningful way, people are likely to overestimate the frequency and impact of that and other problems in the elections more generally,' Fernanda Buril, of the Washington-based International Foundation for Electoral Systems, said in an e-mail.