Argentine voters have forced a runoff between the two top candidates to succeed President Cristina Fernández, a polarizing leader.
With 80 percent of polling places reporting early Monday, opposition candidate Mauricio Macri and ruling party candidate Daniel Scioli each had 35 percent of the votes. Sergio Massa, a former Fernández loyalist who broke away to form his own political movement, was third in the six-candidate field, with 21 percent.
At least 70 percent of the 32 million registered voters cast their ballots during 10 hours of voting, authorities said on Sunday.
Under Argentine electoral law, in order to win outright, a candidate must claim more than 45 percent of the vote, or at least 40 percent with a margin of 10 points over the runner-up.
The Nov. 2 runoff will be the first in the country's history, and Scioli and Macri will now vie for Massa's backing.
Scioli, the governor of the Buenos Aires province and a former vice president, had been viewed as an easy front-runner thanks to the support of Fernández, who won admirers for rewriting Argentina's social contract but also drew sharp criticism for widespread allegations of corruption and numerous economic ills, such as high inflation.
Numerous polls had predicted Scioli would win by more than 10 points, indicating the only question was whether he could gain enough votes to avoid a runoff.
The strong showing by Macri, the mayor of Buenos Aires, underscored that many voters are ready for change after 12 years Fernández and her late husband and predecessor as president, Nestor Kirchner.
Macri campaigned as the candidate to put Argentina's economy in order, promising to resolve a long-running fight with U.S. creditors and lift unpopular currency restrictions.
Scioli, a former boat racer who lost his right arm in an accident in 1989, has bristled at suggestions that Fernández would continue to dominate behind the scenes.
When Argentina's next president takes office on Dec. 10, he will inherit a country troubled by inflation, an overvalued currency and an economy facing what the International Monetary Fund predicts will be a 0.7 percent contraction next year.
Argentina, Latin America's largest economy after Brazil and Mexico, is still waging a legal battle against two American hedge funds that reject its plans to restructure the $100 billion in debt it defaulted on in 2001.
The firms, which Fernández condemns as “vulture funds,” successfully sued for full payment in U.S. federal court. Her refusal to pay them pushed Argentina into a new default last year.
Al Jazeera with wire services