Buenos Aires, Argentina (CNN) -- Early returns in Argentina's presidential primary Sunday showed President Cristina Fernandez de Kirchner is likely to win, moving her closer to re-election.
With nearly 20% of ballots counted, Fernandez, who has led Argentina since December 2007, had 49% of the vote, the Interior Ministry reported.
Ricardo Alfonsin garnered 13.3%, while former President Eduardo Duhalde claimed 12.1% of the vote in the country's first-ever presidential primary, according to early results.
The three will likely face off against four other candidates in the presidential election on October 23. Candidates must get at least 1.5% of the overall vote Sunday to be on the October ballot.
"We have all contributed to increasing democracy today," she said. "Today, Argentina is a freer and more open country than any time since democracy returned in 1983."
Sunday's primary was viewed as a litmus test of Fernandez's popularity and a strong indication as to whether she will win re-election outright in October or face a runoff election on November 20.
Analysts say that if she is able to garner 45% of the vote in Sunday's primary she would be hard to beat in October.
"Cristina Fernandez de Kirchner's victory in the primary demonstrates that Argentine society values her, and that many feel that the best thing is for her to continue for four more years," political analyst Ignacio Labaqui told CNN before the final results were tallied.
Argentinians braved long lines and cold weather as they went to the polls to choose from 10 presidential candidates.
Fernandez voted in her home city of Rio Gallegos, in the Patagonian province of Santa Cruz, where temperatures on Sunday were below zero. She is seeking a second four-year term.
Polls showed that while Fernandez's popularity has waned, she remained the front-runner.
"This primary not only serves the government so it can define its position, but it also serves the opposition, so they can do some fine-tuning to their strategies and create possible alliances," pollster Graciela Romer told CNN en Español before the vote.
Fernandez needs 45%, or at least 40% and a 10-point lead, over her nearest rival to win outright in October.
Alfonsin, the opposition candidate with the strongest numbers behind Fernandez, voted in the town of Chascomus, in the province of Buenos Aires, where some 40% of national voters live. The son of late President Raul Alfonsin, he is a member of the Radical Civic Union Party and is seen as short on significant political experience.
Duhalde, also expected to be among the challengers in October, voted in the city of Lomas de Zamora, in Buenos Aires province. He posed for cameras as he placed his sealed ballot in the box.
"I am happy to have been able to come and cast my vote in this important primary. I hope a lot of people vote today because that is what we need in a democracy," Duhalde told reporters.
Fernandez, Argentina's first elected female president, was married to former President Nestor Kirchner, who died in October. If re-elected, Fernandez has said her second term will be dedicated to her late husband's memory.
Voting is obligatory in Argentina, and some 28 million people were eligible to vote in Sunday's primary.