Former U.N. secretary general Ban Ki-moon, now considering a run for president of South Korea, waves to his supporters as he leaves a news conference at Incheon International Airport. (Kim Hong-Ji/Reuters)

Since Ban Ki-moon returned to South Korea this month — to a hero’s welcome, his arrival at Seoul’s main airport broadcast live on television — the former U.N. secretary general has gone through all the steps required to run for the presidency. But, as the career bureaucrat is quickly finding out, following the traditional playbook doesn’t necessarily equal political success.

He’s followed Confucian rites, visiting his father’s grave and his mother’s house, and mixed them with politics, paying his respects at the tombs of six former presidents.

He’s consulted with the living ones, too, notably going last week to see Lee Myung-bak, the conservative who led the country until 2013 and still has a strong political network. And he talked on the phone with Park Geun-hye, the current president, who is awaiting a court decision on whether she will be impeached amid a sensational corruption and influence-peddling scandal.

He’s held babies and fed old people, visited bustling markets and bowed at Buddhist temples.

It now seems clear that it’s a matter of when, not if, Ban announces his plan to run for the presidency.

“You will hear about it later,” Ban told The Washington Post when asked about his plans during a whistle-stop trip through the national cemetery in Daejeon on a recent day.

Having vowed to work for a “change in politics” and having declared that he would “burn” himself for the nation, Ban is expected to make an announcement next week, after the lunar new year holiday.

If Park is impeached, the next presidential election must be held within 60 days of the court’s decision. But even if she is not, the next election was due to be held in December anyway.

[ With talk of Ban running for South Korean presidency, his home town is abuzz ]

Before the corruption scandal revolving around Park broke in October, Ban’s prospects for winning the presidency appeared extremely good. He was regularly coming in at the top of the polls, despite not having declared an intention to run, and the South Korean press was full of breathless conjecture about his future.

But he has been hurt by his closeness to Park — the two had repeated meetings last year, viewed here as a sign that they were hatching a handover plan — and by allegations of corruption close to him.

The United States has indicted Ban’s younger brother and his nephew on charges of bribery related to the sale of a high-rise building in Vietnam, and it has asked South Korea to extradite them both. Ban denies any knowledge of such a scheme.

The former secretary general has also experienced some bumps upon his return. He was mocked on social media for trying to put two bank notes into a train-ticket machine at the same time — something you can’t do in South Korea — and for wearing a bib while feeding a nursing-home resident. “Netizens,” as Internet users are known here, say that he’s out of touch or that he became too American during his decade in New York.

Ban is now regularly coming in second in opinion polls, behind Moon Jae-in, the leading liberal candidate. The latest RealMeter poll put Moon’s support at 29 percent, to Ban’s 20.

But the biggest challenge that faces Ban, who has no domestic political experience, is building a political base in a country where networks are everything, analysts say.

Since the National Assembly’s vote to impeach Park, Ban has been seeking to distance himself from the conservative factions that remain loyal to her. But other right-wing factions consider Ban insufficiently conservative — citing, for example, his support for LGBT rights while secretary general — and progressives feel burned by Ban’s previous alignment with Park’s conservative ­party.

[ South Korean court to begin considering president’s impeachment ]

Ban has appeared to be trying to have it both ways, describing himself as a “progressive conservative.” On Friday, Ban visited the leaders of both the ruling conservative Saenuri Party and the minor opposition People’s Party. He’s also said to be talking to the new Bareun, or “righteous,” party, formed out of defectors from Saenuri after Park’s fall from grace.

He’s now deciding whether to join a party, form a new party or run as an independent, said Yook Dong-il, a professor of government at Chungnam National University who coordinates groups of Ban supporters.

“He hasn’t announced that he’s running because he hasn’t settled on the party. Party is very important because he needs to have momentum when he makes the announcement,” Yook said.

Ban’s apparent strategy to “go broad” and encompass different factions is not working, said Song Ji-young, a research fellow at the Lowy Institute in Sydney and a former consultant to the U.N. commissioner for human rights.

“Especially after the corruption scandals, Korean voters really want someone who can change the entire political landscape in Korea. Ban doesn’t represent that,” she said, noting what she considers his lackluster record of reform at the United Nations.

[ South Korea’s parliament votes to impeach president over corruption scandal ]

The allegations of corruption in Ban’s family are not helping either. Amid the corruption scandal surrounding Park, South Koreans are demanding increased transparency from presidential hopefuls, and Ban is falling short with his silence on his brother’s situation, the JoongAng Ilbo newspaper said in an editorial Monday.

Ban must explain why he failed to stop his brother taking advantage of their family ties, or, if he knew about the “shady deals,” explain why he failed to stop them, the conservative newspaper said. “That’s the minimum he can offer to Koreans who have been outraged over the scandal involving President Park’s inner circles.”

Although his image has lost some of its shine since he began his homecoming tour, Ban still has plenty of admirers here.

“Ban is the perfect person to be the president because he has served as the leader of the world and did it well,” said Park Wol-soon, the co-founder of a Ban fan club, who was there to greet him at the cemetery in Daejeon, not far from Ban’s home town.

“I’m so relieved he’s come back to South Korea and is going to run for president,” she said. “He will be a stable leader.”

Yoonjung Seo contributed to this report.

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