He was initially hesitant to run in South Korea's presidential race, but when Ban Ki-moon withdrew his bid on Wednesday, the decision took his rivals by surprise.
Ban's star power had declined in an intense political climate, reeling from impeachment charges against President Park Geuyn-hye, the Journal noted.
"For the past three weeks, I have devoted everything I had, but my genuine patriotism and passion were damaged by rumors and fake news", Ban said in a hastily arranged press conference at the National Assembly after meeting with the leaders of three political parties.
"I will give up my pure aspiration to achieve a change in politics under my leadership and unify the country", Ban said. If she is thrown out, presidential elections, originally set for December, would instead be held within two months.
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The latest polls showed the 72-year-old with 13% of the votes, less than half of that of the Liberal Party's Moon Jae-in, who is now the front-runner for the position, according to The Washington Post. His clean image and worldwide profile were dealt a blow with the indictment of his brother Ban Ki Sang and a nephew in the United States, in a bribery scheme involving a Vietnamese development project.
The former United Nations chief's decision could boost the chances of minor candidates such as Mr Ahn Cheol Soo of the progressive People's Party, said Dongguk University political science professor Kim Jun Seok.
Mr Ban appeared to have significant support early in an unofficial campaign and was at one time the perceived frontrunner, but his approval ratings fell sharply as he faced criticism about his political competence. "And people felt (he) should not be a president".
Ban returned to South Korea on January 12 after serving 10 years as United Nations chief but had been unable to capitalise on his much-anticipated homecoming, cutting a sometimes-irritable figure in public and mired in a series of perceived PR gaffes and a scandal involving family members.