Argentina's presidential election is headed for a November 22 runoff between incumbent Cristina Kirchner's chosen successor Daniel Scioli and conservative rival Mauricio Macri, partial results indicated.
Business favorite Mauricio Macri led the count with 36 percent of the vote to 35 percent for Scioli, with just more than two-thirds of polling stations reporting - though most results from Scioli's stronghold, Buenos Aires province, have yet to arrive.
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 runoff will be the first in the country's history.
Al Jazeera's Teresa Bo, reporting from Buenos Aires, said Argentineans are voting for what affects them, such as inflation and insecurity.
"These results are, of course, very surprising for people in Argentina," Bo said.
"Scioli will probably go up two points. But there is still a runoff"
Bo said those who supported Scioli have been disappointed because they were expecting he would get more votes, while others claim they are ready for November's runoff.
"Analysts here say the big challenge is the power Cristina Kirchner will have once she hands over the Presidency to whomever wins in November," Bo added.
Earlier, five major television broadcasters put Scioli in the lead as counting got under way.
Polling stations closed at 21:00GMT, after 10 hours of voting. At least 70 percent of the 32 million registered voters cast their ballots, authorities said on Sunday.
Related: Argentina bids farewell to 'Kirchnerismo'
The final opinion polls before the vote put Scioli at about 40 percent, with Macri at around 30 percent.
Presidential challenger Sergio Massa, who almost certainly placed third, congratulated his rivals on their result and vowed to remain in the political fight.
The vote appeared to be heading towards a second round next month, and both Scioli and Macri will now vie for Massa's backing.
"I want to congratulate Daniel and Mauricio. In three weeks, Argentineans will surely have to chose their path. We know what part we will play," Reuters quoted Massa as saying to his supporters.
Core of 'Kirchnerism'
Scioli served as Nestor Kirchner's vice president from 2003 to 2007, while Macri, 56, is a former football executive.
Scioli has vowed to defend the core of "Kirchnerism", a populist creed built around trade protectionism, social welfare and defence of the working classes.
But he has also promised a change in style to attract more investment and increase productivity.
Macri for his part has vowed to put an immediate and decisive end to what he calls the Kirchners' heavy-handed economic policy and confrontational politics.
Sergio Massa, a former Kirchner ally, is running in the third place.
Nestor Kirchner, who came to office in 2003, is credited to have turned around the economy after a devastating financial crisis that had forced the country to default.
He was succeeded by his wife Cristina, a fiery former senator, in 2007. Nestor died of a heart attack in 2010.
The next president 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 third-largest economy after Brazil and Mexico, is also still waging a messy legal battle with two American hedge funds that reject its plans to restructure the $100bn debt it has defaulted on in 2001.
Source: Al Jazeera and agencies