South Koreans will elect a new president on Tuesday to cap six months of turmoil triggered by a shock martial law briefly imposed by former leader Yoon Suk Yeol that marred the country's reputation as a vibrant, if at times chaotic, democracy.

The new leader will face the challenge of rallying a society deeply scarred by the attempt at military rule and an export-heavy economy reeling from unpredictable protectionist moves by the United States, a major trading partner and a security ally.

Turnout is expected to be high with polls open from 6 a.m. to 8 p.m. following early voting on Thursday and Friday when more than a third of the 44.39 million eligible voters cast their ballots.

Both liberal frontrunner Lee Jae-myung and his conservative rival Kim Moon-soo have pledged change for the country, saying a political system and economic model set up during its rise as a budding democracy and industrial power are no longer fit for purpose.

Their proposals for investment in innovation and technology often overlap, but Lee advocates more equity and help for mid-to-low-income families while Kim has campaigned on giving businesses more freedom from regulations and labor strife.

Overshadowing any economic or social policy initiatives, however, is Yoon's botched attempt to impose martial law that has loomed large over the poll.

Lee has called the election "judgment day" against Kim and his People Power Party accusing them of having condoned the martial law attempt by not fighting harder to thwart it and even trying to save Yoon's presidency.

Kim was Yoon's labor minister when Yoon declared martial law on Dec. 3.

The conservative Kim, on the other hand, has branded Lee a "dictator" and his Democratic Party a "monster," warning if the former human rights lawyer becomes president, nothing will stop them from working together to amend laws simply because they do not like them.

Lee is favored to win, according to polls released a week before the vote, leading Kim by 14 percentage points with 49% public support in a Gallup Korea survey, although Kim had narrowed an even wider gap at the start of the campaign on May 12.

Exit polls conducted by three television networks will be released at the close of the polls at 8 p.m. Ballots will be sorted and counted by machine first, then triple-checked by election officials by hand to verify accuracy.

It was not clear when the result would emerge. In 2022, Lee conceded to Yoon at around 3 a.m. the day after the vote in the closest presidential race in the country's history, which was decided by a margin of less than 1 percentage point.

The National Election Commission is scheduled to certify the result on Wednesday and the winner's inauguration is expected within hours. There will be no presidential transition as the office has remained vacant since Yoon was impeached by parliament and then removed by the Constitutional Court on April 4.