SANTIAGO As Chileans head to voting booths on Sunday to pick who will lead the country for the next four years, the biggest question mark is whether former President Michelle Bachelet wins outright or needs to wait for a December runoff.
The center-left Bachelet has promised to narrow the worst income inequality among the 34 member states of the Organization for Economic Co-Operation and Development by leveling the playing field in education. She has also pledged to upend a constitution that dates back to Augusto Pinochet's 17-year dictatorship.
Her Nueva Mayoria (New Majority) coalition, which spans the political spectrum from communists to moderate Christian Democrats, must also win big in congressional elections on Sunday in order to muster the political might needed to implement those changes.
"In order to confront inequality, I invite you to vote en masse for the Nueva Mayoria this Sunday. We want to win in the first round because we have a lot of work to do," Bachelet told a packed crowd at her campaign's closing ceremony on Thursday.
Trailing a distant second to the 62-year-old Bachelet in the polls is Evelyn Matthei, 60, the candidate for the governing right-wing Alianza coalition.
A candidate winning over half the votes would be elected outright - something that has not happened in 20 years. Otherwise, the two top contenders will go head to head on December 15.
One recent poll of likely voters suggested Bachelet may get the votes she needs for a first-round victory.
But other polls have shown that support for the eight other candidates, including Matthei, maverick economist Franco Parisi and former socialist congressman Marco Enriquez-Ominami, could fracture the vote and push Bachelet into a second round against Matthei.
In any case, pollsters and political analysts believe Bachelet would easily win a runoff against Matthei. Bachelet, who held the presidency from 2006 to 2010, was constitutionally barred from seeking immediate re-election after her first term, but left office enjoying stratospheric popularity.
The Andean country, the world's top copper producer, moved to a voluntary voting system from a compulsory one last year, injecting a dose of uncertainty into electoral forecasts.
All 120 lower house seats and 20 out of 38 Senate seats are also being contested on Sunday. Under the Chilean system, the governing coalition needs more than a simple majority to pass some kinds of legislation, making it easier for the opposition to block key reforms - a Pinochet-era legacy that Bachelet wants to change.
In a bid to curb Alianza's power, Bachelet has been urging voters to back her coalition's congressional candidates. Still, she is bound to face tough negotiations with the right to steer through her proposed reforms.
ROAD TO THE PRESIDENTIAL PALACE
Bachelet proposes to raise corporate taxes to 25 percent from their current 20 percent and close a business tax loophole to finance an education overhaul. Matthei contends that could hurt economic growth and slow corporate investments.
Chile has boasted average annual economic growth of over 5 percent and made enormous headway toward eradicating extreme poverty in the more than 20 years since the return to democracy.
But the mining powerhouse - home to a third of global copper output and some of the region's most powerful companies, including LATAM Airlines, retailer Cencosud and industrial conglomerate Empresas Copec - still has work to do to join the ranks of developed countries.
Its highly stratified education system was at the heart of student protests that exploded in 2011 to demand free and improved schooling, shaking the political and business elite. Camila Vallejo, who shot to fame as the face of the student movement, is running for a seat in the lower house on Sunday.
"Inequality is Chile's huge scar," Bachelet told the spirited, flag-waving crowd on Thursday. "It's our main obstacle and the stone in our shoe when we really think about becoming a modern country."
Bachelet's down-to-earth, affable manner and her personal history, which is intimately tied to the nation's tumultuous past, have helped propel her past Matthei.
Bachelet and her father were victims of torture during the Pinochet years, while Matthei's father was a general in the dictatorship's 1973-1990 junta.
That association, along with Matthei's penchant for off-the-cuff expletives, her late entry into the presidential race and public disenchantment with incumbent President Sebastian Pinera, has hurt the right-wing candidate's chances.
Votes will be cast from 8 a.m. to 6 p.m. local time (1100 to 2100 GMT) and the first partial results are scheduled to be reported by the national electoral service at 7:30 p.m. (2230 GMT) or when 20 percent of votes have been counted.
(Reporting by Anthony Esposito; Editing by Peter Cooney)