Argentines are voting in elections to choose their next president, the successor to President Cristina Fernandez de Kirchner, who dominated national politics for 12 years along with her late husband, Nestor Kirchner.
Recent surveys show candidate Daniel Scioli, Fernandez's chosen successor, close to the 40 percent threshold for him to win outright, providing his lead is 10 points over his nearest rival.
Scioli has vowed to uphold the core elements of "kirchnerism," a populist creed built around trade protectionism, social welfare and defense of the working classes.
Scioli's main rival is 56-year-old Mauricio Macri, the center-right mayor of Buenos Aires and former boss of the popular football club, Boca Juniors.
Macri wants to lift capital controls and trade restrictions to win investor confidence and bring hard currency into the dollar-starved economy.
Scioli, the 58-year-old Buenos Aires provincial governor and powerboating fanatic who lost his right arm in a 1989 racing accident, has also promised a change in style to attract more investment and increase productivity, and has assembled an economic team of free-market advocates.
He talks of a more gradual approach to monetary reform, while maintaining a generous social welfare safety net.
Opinion polls have put Scioli at about 40 percent, with Macri at around 30 percent.
An additional 22 percent said they would vote for Sergio Massa, a former Fernandez loyalist who fell out with the president and launched a rival party, the Renewal Front, two years ago.
Under Argentine electoral law, in order to win outright in the first round, 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.
That means the country could be headed for its first-ever run-off election, on November 22.