After the polls closed on Sunday, local media cited exit polls that suggested that Daniel Scioli (pictured above) of Fernandez' Front for Victory party had taken the most votes in the primary, followed by opposition candidate Mauricio Macri of the Let's Change Coalition.

Sergio Massa, a former member of Fernandez' party, now running under the United for a New Alternative ticket, was thought to be in third. Initial results were expected in a few hours' time.

Unlike US primaries, the voters in Argentina don't have to vote for candidates from their own parties, but are free to cross party lines, making it something of a dry run for the October 25 presidential vote.

Scioli, who advocates "gradualism" as the way to roll back the heavy government control of the economy imposed by Fernandez, who has been in office for the past eight years. She has carried on the family "dynasty" after succeeding her husband, Nestor Kirchner, in 2007, after he was in office for just one four-year term.

Macri, on the other hand, has pledged that if elected, he would quickly free up the financial markets.

Scioli the frontrunner

Scioli, who is the governor of Buenos Aires province, is seen as the frontrunner for the election, but Macri, the capital's mayor, may have enough support to force a run-off in November. This could leave Massa as the eventual king-maker. Fernandez was barred under the constitution from seeking a third consecutive term, but would be eligible to take another run for the presidency in 2019.

Voters in some parts of the country were forced to brave heavy rains to get to the polling stations, some of which had to be relocated due to flooding in the greater Buenos Aires region. Voting in the primary is mandatory, but those who fail to comply only face a small fine.

Argentina continues to struggle with economic problems, with inflation running at around 20 percent.

pfd/gsw (AP, Reuters, AFP)