Image copyright AFP Image caption The poll has split the nation in two
Chilean president Sebastian Pinera is vying to get back into office after a near-certain defeat at the ballot box by opposition candidate Michelle Bachelet.
The vote, which took place on Sunday in the world’s No 4 copper exporter, has been called the most important since the 1973 military coup.
Pinera and Ms Bachelet led in a first round vote on 5 April, but the opposition leader won by a slim margin.
If they qualify for a run-off vote, it will take place on 15 April.
Roughly 20% of Chileans said they would vote for Ms Bachelet, putting her in pole position for a second round.
Her opponent is seen as moderate and less polarising than the outgoing president, who leads with 36.15%, according to the latest poll.
Chile has a history of popular presidents breaking with the authoritarian, 1970s-1990s regime of Gen Augusto Pinochet, which left thousands dead and disappeared.
And although the presidential election on Sunday was the first without a ballot paper by Gen Pinochet, it was labelled a “constitutional farce” by one of Ms Bachelet’s allies and probably produced one of the tightest races in Latin America.
“I’m doing this for the next 10 years to finish my term, but also for generations to come,” Ms Bachelet told a boisterous crowd on Sunday.
Image copyright AFP Image caption Sebastian Pinera is seeking to put Chile back on the map as a country of great leaders
“This is why I will work as hard as I can to ensure that we can finally build a Chile that is not just solid, but also noble and progressive,” she said, appealing to her supporters to turn out to vote in the run-off.
“Chile has never been a country without experience in a peaceful and democracy way,” she added.
Mr Pinera is trying to recast Chile as a top-ranking nation on the world stage, but will need to find another main business contributor of Chile’s economy if his first term has been successful.
“I am not looking to save the state from crisis, but make it better for Chile’s future,” he said after a first round vote that saw a 47% participation rate.
“Polar opposites give all of us hope for a better future for our children.”
While President Pinera has promised a “grand double act” with opposition politician Sebastian Pinera that would create jobs, encourage growth and diversify the economy, Ms Bachelet has presented herself as a uniting and humble voice that would push Chile to overcome its past.