From 6 a.m. Wednesday, voters will go to the polls to elect a new president. The winner of the race, seen one of the closest in history, should become clear as early as 11 p.m., election officials said Tuesday.

Polling will take place at 13,542 polling locations across the country over 12 hours till 6 p.m, the National Election Commission said. Nearly 40.5 million Koreans are eligible to vote.

Two candidates ― Park Geun-hye of the ruling Saenuri Party and Moon Jae-in of the main opposition Democratic United Party ― are running neck-and-neck for the top job in a race that has pitted the old and conservative voters against the young and liberals.

Political analysts say voter turnout may decide the winner. A higher participation rate would brighten the chances of Moon pulling off a dramatic come-from-behind win.

In a survey conducted by the NEC, nearly 80 percent of respondents said they would definitely vote, but the actual turnout tends to be lower, the pundits say.

The turnout in previous elections stood at 63 percent in 2007 and 70.8 percent in 2002.

Cold and frosty weather is forecast on election day, which could discourage some voters from heading out. Temperatures in Seoul are expected to drop to as low as minus 10 degrees Celsius in the morning, with daytime highs remaining well below zero, at around minus 4 degrees.

The vote count will start immediately once polls close. It is expected to be completed by around 2 a.m. the next day. An electronic ballot counting system will be used as in previous elections.

Together with the presidential vote, reelections or by-elections are to be held in 26 constituencies across the country to elect Seoul’s education superintendent, governor of South Gyeongsang Province, three heads of local administrative bodies and 21 provincial councilors.

By Lee Sun-young (milaya@heraldcorp.com)