Backgrounder: Argentina's leading presidential candidates

There are three front-runners for Sunday's presidential vote in Argentina.

Daniel Scioli of the ruling Front for Victory Party leads the polls with more than 38 percent of support, followed by Buenos Aires Mayor Mauricio Macri of the conservative Cambiemos (Let's Change) Party, with 30 percent, and Sergio Massa of the United for a New Alternative Party (UNA), with 20 percent.

Following are brief profiles of the three:

Scioli, the 58-year-old governor of Buenos Aires province, served as vice president from 2003 to 2007 during the government of late President Nestor Kirchner. Prior to that, he served as secretary of sports and tourism.

He is expected to largely continue the policies of Kirchner's successor and wife, Cristina Fernandez, but has also signalled his willingness to break with past formulas, saying: "we are going to maintain what has to be maintained, and change what has to be changed."

The son of an Italian-born business magnate, Macri, 56, successfully served as president of top football club Boca Juniors for 13 years before becoming national deputy and later mayor of Buenos Aires.

In the high-profile job of mayor since 2007, he became the face of Argentina's conservative opposition, and often clashed with the federal government over policies. In 2011 he was re-elected mayor with more than 64 percent of the vote in a runoff

The youngest of the three, the 43-year-old Massa is a political centrist who served as Fernandez's chief of staff for a year from 2008 to 2009.

Once described by media as "a former liberal," he also used to serve as head of the national social security agency and has been mayor of the town of Tigre in Buenos Aires province since 2009. Endi