Declared the winner by a margin of less than 1 percent, Mr. Oh issued a statement in which he said he “in reality was defeated.” His opponent, Han Myeong-sook, who had been a prime minister in the previous liberal government under the late President Roh Moo-hyun, declared “the people of Seoul and the nation have won” even though “I may have lost.”
Oh did not pull ahead in the count until early Thursday when the National Election Commission said he had 47.43 percent of the votes as opposed to 46.83 percent for Ms. Han. The close vote may well have eliminated him as a possible conservative candidate in the 2012 election to succeed Lee, barred by the Constitution from a second five-year term.
A factor in the resurgence of the opposition was the desire of younger voters for change. All told, 54.5 of the electorate went to the polls, the highest percentage in 15 years. Many older voters, more likely to support the conservatives, stayed home or enjoyed the holiday that was set aside for voting.
Oh had earlier been viewed as an easy winner in elections in which Lee’s popularity was believed to have risen on the strength of his strong stance against North Korea. The government on May 20 announced the results of an investigation showing that a North Korean midget submarine had fired the torpedo that sunk the Cheonan in disputed waters in the West or Yellow Sea.