The election sees Peronist Economy Minister Sergio Massa, at the helm for the country's worst economic crisis in two decades, go head-to-head with radical libertarian outsider Javier Milei, the slight pre-election favorite in the polls.
"The election will mark a profound rupture in the system of political representation in Argentina," said Julio Burdman, director of the consultancy Observatorio Electoral.
Massa, 51, an experienced political wheeler-dealer, has been clawing back votes with tax cuts and campaigns highlighting Milei's radical plans to slash state spending.
In the first-round vote in October, Massa won 36.7% of the votes compared to some 30% for Milei.
The libertarian has since won public backing from third-place finisher Patricia Bullrich, though it's by no means certain all her votes will shift to him.
Persons:
Sergio Massa, Javier Milei, Milei, Massa, Julio Burdman, he's, Matias Kawior, South, Santiago Neria, Patricia Bullrich, Nicolás Misculin, Candelaria Grimberg, Rosalba O'Brien
Organizations:
Peronist, Massa, International Monetary Fund, Thomson
Locations:
BUENOS AIRES, China, United States, Brazil, Argentina, Buenos Aires