However, they were brought forward after the decision of the Constitutional Court on 10 March 2017 to uphold the National Assembly's impeachment of Park.

Following procedures set out in the Constitution of South Korea, Prime Minister Hwang Kyo-ahn succeeded Park as the acting president.

After Park was removed from office by the Constitutional Court's ruling, acting president Hwang announced he would not run for a term in his own right.

[2][3][4] Opinion polling before April consistently placed the Democratic Party's candidate, Moon Jae-in, runner-up in the 2012 election, as the front-runner.

Second place in the opinion polls was initially held by former UN Secretary-General Ban Ki-moon, who declined to run in February, followed by Ahn Hee-jung, whilst he lost the Democratic primaries to Moon.

[5][6][7] and the Nikkei Asian Review noted that, in the wake of her "crushing defeat", "rivals sense a prime opportunity to complete the power shift in the December 2017 presidential vote".

On 10 March 2017, Park was formally removed from office, with a unanimous ruling by all eight of the Constitutional Court's justices supporting her impeachment.

Ballot numbers for independent and minor party candidates were determined through a random lottery by the National Election Commission.

By the time of the polling blackout period began on 3 May, Ahn and Hong were recording similar levels of support.

He assumed the office as the President of South Korea immediately upon the confirmation of the results at 8:09 am on 10 May 2017 (Local time) and was inaugurated in the National Assembly at afternoon on the same day.