Conservative billionaire Sebastian Pinera will face center-left Senator Alejandro Guillier in a runoff for Chile's presidency next month, after a first round vote on Sunday that Pinera won, but with fewer votes than expected.
Both candidates would keep in place the top copper exporter's longstanding free-market economic model, but former president Pinera has promised investor-friendly policies to turbocharge growth, while Guillier wants to press on with outgoing President Michelle Bachelet's overhaul of education, taxes and labor.
With over 98 per cent of votes counted, Pinera, a 67-year-old businessman, had clinched 36.6 per cent, falling short of the 50 per cent needed for an outright victory, Chile's electoral agency Servel said.
Guillier, a 64-year-old bearded former TV news anchor elected to the Senate in 2013, had 22.7 per cent, just over two points ahead of the third placed candidate, leftist Beatriz Sanchez, whose better than expected showing will likely ensure her Frente Amplio coalition will yield sway in Congress.
Pinera's result was below pollster expectations, indicating that the December 17 runoff will likely be a more closely-fought contest than previously forecast, especially if Guillier can rally supporters of Sanchez and four other left-leaning rivals behind him.
"We're going to have a very competitive second round," Pinera's campaign chief Andres Chadwick told journalists on Sunday evening.
The most recent opinion survey by CEP last month had forecast Pinera securing 42 per cent of likely votes in the first round, and easily defeating Guillier in the runoff.
After a divisive race, Guillier called for "profound unity" to unite Chile's fractured left against Pinera.
"There are more of us, and therefore we must win in December!," Guillier told his cheering supporters.
Sanchez did not endorse Guillier in a fiery speech before her followers, even as she pilloried his opponent. "Sebastian Pinera is a step backward for the country and the country is going in a different direction!" Sanchez said.
But Pinera, who previously led Chile between 2010 and 2014, flashed the optimism he has shown on the campaign trail, where he has repeatedly plugged his campaign slogan "better times."
"This result is very similar to the one in 2009. And you'll remember that in 2009 we won the election," Pinera said, before a buoyant crowd.
Voter turnout was higher than expected, a factor which analysts forecast will count against Pinera if repeated in a runoff.
Bachelet cannot run again this year because of term limits. Guillier was one of two candidates her center-left coalition Nueva Mayoria backed in the first round.
Speaking from the presidential palace on Sunday evening, she urged Chileans to vote in December, saying her policy changes were at stake.