Backgrounder: Process for S.Korea's presidential election

South Korea is set to hold a presidential election on Tuesday to replace former President Park Geun-hye who was impeached and arrested in March over corruption allegations.

The election to pick the country's next leader was originally scheduled for Dec. 20 but it would be held ahead of schedule for the impeachment of Park.

The constitutional court upheld the bill to impeach Park on March 10, which was passed in the parliament on Dec. 9, 2016. Three weeks later, Park was taken into custody on bribery charges.

With a president being unseated, a presidential by-election is required to be held in 60 days.

Following is the election process based on schedules released by the National Election Commission:

As the by-election was required for the impeachment, preliminary presidential candidates began to register with the election commission on March 10.

Ten days later, the election date was fixed at May 9 and was designated as a temporary holiday.

The country's election to pick a new president had been held in December since the constitution to end the past military dictatorship was introduced in 1987.

A new president had been inaugurated in February after a 70-day transition period, but the next president would take office right after the election result comes out without the usual transition period.

From the next election to select the president, it will be held in March to allow for the transition period.

From April 15 to April 16, presidential candidates officially registered with the national election commission.

In early April, all of the country's five major political parties ended a series of regional primaries to field a single candidate who represents their respective parties.

A total of 15 candidates registered with the election commission, the highest-ever in history. Two candidates have withdrawn their runs for presidency until now.

On April 17, the three-week official campaign period kicked off. The campaign trail was slated to end on Monday.

Three official TV debates have since been held among five major candidates who met the requirements set by the election commission, including a candidate of a party having more than five lawmakers.

Under the election law, at least three TV debates are required to be broadcast nationwide. Three more nationally-televised debates have been held.

From May 4 to May 5, an early voting had been conducted to enable voters incapable of casting ballots on May 9 to vote for their favorites in advance.

The early voting system was adopted in 2013, and was first applied to this year's presidential election. The voting rate was a whopping 26.06 percent, indicating a great public attention to the election.

On May 9, the voting hours will be expanded by two more hours compared with the 2012 presidential election. The voting will be conducted from 6:00 a.m. local time (2100 GMT Monday) to 8:00 p.m. local time (1100 GMT) on Tuesday. Counting will begin right after close of polls. Endit