Voting began Sunday in the first round of Chile's presidential election, with former president Sebastian Pinera likely to cement his frontrunner status to succeed Socialist leader Michelle Bachelet.

But it was unclear whether Pinera, a 67-year-old billionaire who was president from 2010-2014, would gain enough support to avoid a runoff against the runner-up -- likely to be Alejandro Guillier, an independent supported by Bachelet's Socialists.