Alberto Fernández has been elected president of Argentina in a vote dominated by economic concerns.
The center-left opposition candidate secured more than the 45% of the vote needed to win, beating conservative incumbent Mauricio Macri.
Raucous crowds gathered at Alberto Fernández’s election headquarters to celebrate the result.
The vote was held amid an economic crisis that has left a third of Argentina’s population in poverty.
Mauricio Macri had trailed behind his challenger in pre-election polls and was trounced by the opposition in primary elections in August.
The incumbent president conceded defeat on October 27. Congratulating his political rival, Mauricio Macri said he had invited Alberto Fernández to the presidential palace on October 28 to discuss an orderly transition.
Alberto Fernández later told supporters he would collaborate with the outgoing president “in every way we can”, according to Reuters.
With more than 90% of ballots counted, Alberto Fernández had 47.79% of the vote, compared to Mauricio Macri’s 40.71%.
To win in the first round, a candidate needs at least 45% of the vote, or 40% and a 10-point lead over the second-place contestant.
Alberto Fernández will assume the presidency on December 10.
The vote was dominated by concerns over the economy. With nearly one in three people now living in poverty, voters backed the candidate they thought was best-placed to lead Argentina out of the crisis.
Mauricio Macri promised to achieve “zero poverty”, but things actually worsened during his four-year rule. His supporters say he inherited a broken economy when he came to power and needed more time to sort it out.
Alberto Fernández has vowed to play things safe financially.
Career politician Alberto Fernández has caused quite a stir since he first appeared in the limelight of Argentine politics some six months ago.
The former campaign strategist began his bid for the presidency in May – something of a surprise as ex-president Cristina Fernández de Kirchner had been widely tipped to be the center-left opposition coalition’s candidate for the top office.
However, Alberto Fernández really came into his own in August when he defeated Mauricio Macri by nearly 15 percentage points in primary elections, a compulsory vote for all electors which is seen is a dry-run for the presidency.
Argentine President Cristina Fernandez de Kirchner has made an emotional farewell speech to supporters in the capital, Buenos Aires.
The outgoing president urged people to take to the streets if they feel betrayed by the new center-right government.
Conservative Mauricio Macri, who won a run-off election last month, is due to be sworn in as president later.
Mauricio Macri inherits problems including high inflation and a low level of foreign currency reserves.
He has promised a new era of change and reconciliation.
Addressing tens of thousands of cheering supporters outside the La Casa Rosa presidential palace in Buenos Aires, Cristina Fernandez de Kirchner defended her record.
“We believe in what we have achieved so we need to have a positive attitude to ensure that these things will not be destroyed,” she said.
“When you feel that those who you trusted and voted for have betrayed you, take up your flags,” she added.
Cristina Fernandez de Kirchner is to skip today’s swearing-in after the two became embroiled in a row over the ceremony’s location.
It will be the first time since the end of Argentina’s military dictatorship in 1983 that a president has not attended the inauguration of a successor.
Mauricio Macri sought a court injunction affirming that Cristina Fernandez’s term ended at midnight on December 9.
During her speech, Cristina Fernandez de Kirchener joked: “I can’t talk much because after midnight I’ll turn into a pumpkin.”
Power will now be transferred to the new president by Senate Speaker Federico Pinedo, who is acting act as temporary head of state for 12 hours.
Cristina Fernandez de Kirchner and her late husband, Nestor Kirchner, held power in Argentina for 12 years.
She is revered by some Argentines for expanding welfare benefits, nationalizing some companies and introducing new civil rights such as gay marriage.
However, critics say she created a culture of handouts and clogged Latin America’s third-largest economy with interventionist policies.
Mauricio Macri – the outgoing mayor of Buenos Aires and a former president of football club Boca Juniors – defeated Cristina Fernandez’s preferred candidate Daniel Scioli by 51.4% to 48.6% in a run-off vote last month.
He is the first center-right leader to come to power since Argentina returned to democracy.
Mauricio Macri has not detailed his economic policies, but said that he will need to implement swift and radical changes in order to win back market confidence.
However, Cristina Fernandez de Kirchner’s party still holds the most seats in the legislature and could make it hard for him to implement big changes.