Myung Tae-kyun, mysterious power broker who ran a public opinion polling agency, and a screenshot of KakaoTalk messages allegedly sent between him and first lady Kim Keon Hee. Screenshot from Facebook

First lady Kim Keon Hee is under intense scrutiny over her relationship with Myung Tae-kyun, a mysterious power broker, after leaked messages suggest that she exercised undue influence over the ruling party's candidate nominations for the 2022 by-elections and April's general elections.

On Tuesday, Myung disclosed a screenshot of KakaoTalk messages allegedly sent between him and the first lady. In an undated message, Kim apologizes to Myung on behalf of "oppa" (a Korean term that translates to "older brother," but often used to refer to one's boyfriend or husband) while talking about how "oppa" is immature and ignorant.

The presidential office said that the leaked messages were a private conversation between the two and "oppa" refers to Kim's older brother. However, the opposition suspects the term refers to President Yoon Suk Yeol.

The newly leaked messages came after a heated exchange of words with Rep. Kim Jae-won of the ruling People Power Party (PPP), who called him an "anxious dog that barks at everything" and added that he should go to prison.

"I have about 2,000 more messages to share, including my conversation with President Yoon. Some of them are public conversations," Myung said.

In a scandal first published by online media outlet News Tomato, the presidential couple and other political heavyweights of the PPP came under suspicion of receiving help from Myung, a shadowy figure who ran a public opinion polling agency, to win elections.

Among the accused are Seoul Mayor Oh Se-hoon and South Gyeongsang Province Gov. Park Wan-su, who vehemently denied ties to Myung and threatened to take legal action.

This photo shows a list of witnesses to be summoned by the National Assembly's Steering Committee at a parliamentary audit, which includes Myung Tae-kyun, first lady Kim Keon Hee and her older brother. Yonhap

Myung, a self-proclaimed political consultant, claims that he has known Yoon even before the latter entered politics and has recommended personnel appointments, including Choi Jae-hyung as prime minister. He also argued that he played a substantial role in unifying Yoon, then-presidential candidate of the PPP, and Ahn Cheol-soo, then-presidential candidate of the minor center-right People Party.

In addition to allegations of stock manipulation and graft involving a luxury handbag, the first lady has become embroiled in a series of political controversies linked to disclosures by Myung.

The National Assembly's Steering Committee designated Myung, Kim and Kim's older brother as witnesses for a parliamentary audit on Nov. 1 to clear doubts about their connection.

Some PPP lawmakers fear the party's future could suffer from this scandal.

PPP leader Han Dong-hoon made it clear that there is a need to fully address and resolve the issues surrounding the first lady, including alleged interference with the PPP's candidate nominations ahead of the 2022 by-elections and April general elections.

Kim Chong-hyuk, member of the PPP's Supreme Council who is considered part of the pro-Han faction, said: "The presidential office's explanation is a bit absurd. I want to believe its words, but I wonder if that kind of explanation will be persuasive to the public."

The main opposition Democratic Party of Korea (DPK) said the allegations swirling around Yoon's inner circle involve behavior that is not just unbecoming, but illegal.

"It seems undeniable that President Yoon and his wife had a close relationship with Myung Tae-kyun," Rep. Park Chan-dae, floor leader of the DPK, said during a Supreme Council meeting, Wednesday.

"They must reveal what they planned and did with Myung from the presidential primary until now, including the issue of manipulating public opinion polls. The first lady should clearly explain to us who ‘oppa' is. Despite the presidential office's response, nobody believes that oppa actually refers to her older brother."

The minor Rebuilding Korea Party (RKP) said the latest scandal will accelerate the fall of the Yoon administration. "The more they pretend not to see, not to hear and not to know, the more suspicion and distrust toward the president and his wife will grow," he said. "This will only hasten the fall of the regime," Kim Bo-hyup, chief spokesperson of the RKP, said.

Daegu Mayor Hong Joon-pyo called on the opposition parties to reorganize polling agencies in the wake of the scandal involving Myung to prevent opinion manipulation.