Argentine broadcasters have reported exit polls showing Buenos Aires' conservative mayor winning the presidential elections. If confirmed, the victory would mark a significant shift away from leftist politics.
Argentines voted on Sunday in the country's divided presidential runoff, which may see power shift to the opposition after more than a decade.
Several exit polls showed Buenos Aires Mayor Mauricio Macri winning the runoff.
Party insiders at Macri's campaign headquarters estimated that the conservative politician would likely win by a margin of 5 to 8 percentage points, according to the Reuters news agency.
Ruling-party candidate Daniel Scioli came first in the first round of Argentina's presidential elections on October 25.
However, many Argentines appear to want a political shift following 12 years of leftist rule under President Cristina Fernandez de Kirchner, and her late husband, who ruled before her.
Change of style
"Scioli did not manage to differentiate himself from Fernandez and so people stopped seeing him as a change of style and went over to Macri," said Mariel Fornoni, a consultancy firm director and political analyst.
Meanwhile, outgoing President Fernandez did not indicate whether she would continue to lead her party if Scioli lost at the polls.
"I am an activist. I have never seen myself as a leader in anything, I never order anyone anything, so don't get me into a debate that is not fit for a day like this," Fernandez said after casting her ballot.
"The future will be whatever Argentinians decide. Nothing lasts forever," Fernandez added.
Argentina's next president is expected to take office on December 10.
ls/jm (Reuters, AFP, dpa)