Chile's presidential election will go to a December run-off vote, after conservative Sebastian Pinera won the first round but fell short of an outright victory.

Pinera, a billionaire ranked by Forbes magazine as the third richest person in Chile, won 36.6 percent of Sunday's vote. Socialist Alejandro Guillier came second, with nearly 23 percent.

A candidate needs to win at least 50 percent to secure an outright victory.

Pinera served as president from 2010 to 2014, the first conservative to do so since Chile transitioned to democracy from the far-right dictatorship of Augusto Pinochet in the late 1980s.

After two decades of centre-left rule, the Pinera administration heralded pro-business reforms. In 2011, the billionaire president defended for-profit education, in the midst of a nationwide student protest movement which called for the end of private educational institutions.

"Pinera is not well liked. He has [a lot of] negatives, but people think that he governed relatively well, that the country grew, that there was employment, there were opportunities for many people, so they are saying 'Let's give him a chance again,'" political analyst Patricio Navia told Al Jazeera before Sunday's vote.

'Strength for second round'

Guillier comes from the centre-left Nueva Mayoria coalition, the party of Michelle Bachelet, the outgoing president.

Bachelet, who took office in 2014, instituted a number of changes including same-sex marriage, education, pension and tax reforms designed to benefit the working class.

Corruption scandals and the public's impatience with the speed of the reforms dogged Bachelet's presidency, leading to an approval rating of 26 percent.

She cannot run for re-election under Chile's constitution, which prohibits candidates from serving consecutive terms.

The biggest surprise of the election was the success of Beatriz Sanchez, a left-wing candidate who won more than 20 percent of the vote.

While Sanchez has yet to endorse Guillier, she has said that a Pinera presidency would be a "step back" for the country.

"The sum of those who are for changes is more than that of those who want to go backwards, and that already gives us strength for the second round," Guillier told reporters after casting his ballot.

Regional effect

A victory for Pinera would be another blow to the once-powerful Latin American left. Right-wing governments have displaced leftists in Brazil and Argentina.

Venezuela, meanwhile, is undergoing a political and economic crisis, partly due to the low price of oil, which has reportedly caused widespread malnutrition.

Ecuador seemingly bucked the right-wing trend when the country elected Lenin Moreno to succeed populist Rafael Correa in February.

However, Moreno's policies have been criticised as pro-business, causing the Alianza Pais party to remove him in October as their leader.

Correa, who now lives in Belgium, his wife's home country, has called on Moreno to explain his policies.