Lee Ju-ho becomes acting president after a dramatic night saw Han Duck-soo resign to run for presidency and successor Choi Sang-mok suddenly quit to avoid impeachment.
Lee pledges "fair election management" in unprecedented situation where Korea's 4th-in-line now leads nation.
BREAKING: Choi Sang-mok resigns as finance minister just before parliament could vote to impeach him.
With Han Duck-soo also resigning as acting president at midnight, power passes to next-in-line Lee Ju-ho, education minister, who becomes acting president.
Total power chaos.