Allegations that first lady Kim Keon Hee interfered with the ruling party's candidate nominations ahead of April's legislative general election are stirring up the political landscape in South Korea -- and at the center of it all is a pollster who claims he "advised" President Yoon Suk Yeol.

Myeong Tae-gyun became the center of attention after online media outlet Tomato News reported that he had connections with the presidential couple, and played a role in the ruling People Power Party's election nominations.

Then in an interview with the Donga Ilbo newspaper Monday, he claimed that he frequently visited Yoon's Seocho-dong residence in Seoul during the 2022 presidential election and offered political advice.

Myeong also said he recommended personnel appointments, telling Yoon to appoint Choi Jae-hyung, former head of the National Audit Office, as prime minister.

He said his political advice included a recommendation to change your personnel like you change your clothes -- meaning that there are some clothes that need to be changed every day and coats that need to be changed every season. Myeong also claimed that he was offered a position in the presidential transition committee and a government post, but turned them down.

Myung stated that he played a significant role in unifying the presidential candidacies of Yoon, backed by the main conservative bloc, and rival Ahn Cheol-soo.

Myung added that "the regime would be jeopardized if (prosecutors) started investigating him (Yoon)," saying that he would be impeached within a month if that happened. He implied he had critical "smoking-gun" evidence that could jeopardize the Yoon administration.

He also revealed that he had exchanged texts with the first lady even after the presidential inauguration and advised her on how to manage people, ensuring her to "always cross-check, as it would be a risk to make mistakes once Yoon takes office," according to the report.

The first lady is currently facing allegations that she sent a Telegram message to then-five-term lawmaker Rep. Kim Young-sun telling her to run in a different constituency ahead of the April 10 election.

The connection between Kim Young-sun and Myeong runs back to 2022, when the prosecution suspects the former People Power Party lawmaker sent him dozens of payments totaling about 90 million won ($67,000) after she was elected to the National Assembly in a 2022 by-election.

Rep. Shin Sung-num said in a local news article Myeon was a "weird hillbilly who analyzes politics from a unique perspective."

Shin said he felt Myeong "had one of the best political senses" among the people he had met and "excelled in election planning," recalling the first time they met during the 2020 National Assembly election.

"He tends to be a little bumpy because he didn't study regularly, but he seems to have a creativity that regular people don't have," Shin said in the article.

"Only few people in politics in Changwon and other parts of North Gyeongsang Province do not know the name of Myeong Tae-gyun," Newstomato said in introducing Kim.

It added that ex-lawmaker Kim Young-sun "was absolutely dependent on Myeong," as he had helped her win in Changwon, in a seat she had no connection to.

Myeong also claims to have been instrumental in getting Oh Se-hoon to be elected as the mayor of Seoul, and Lee Jun-seok as party leader of the People Power Party, which drew worldwide attention because he was the youngest-ever politician to lead the then-main opposition party.

Myeong added in the interview that Yoon personally sent a man to talk to him.

The 2021 Seoul mayoral by-election was held on April 7, and the party convention for the People Power Party was on June 11. Yoon announced his intention to run for the presidency on June 29.

Opposition party lawmakers are calling for a thorough investigation into Myeong's alleged involvement in political decision-making.

Rebuilding Korea Party leader Cho Kuk told CBS Radio's "Kim Hyun Jung's News Show" on Tuesday that the allegations were serious and needed clearing up.

"It is important to know whether he has intervened in national affairs, such as recommending personnel or proposing policies, since Yoon took office,” he said, adding that if those were confirmed, "it is grounds for impeachment.”

He added that if the President and the first lady were confirmed to have made national decisions or policies based on Myeong's advice, it would make him "the second Choi Soon-sil."

Choi Soon-sil is a South Korean businesswoman known primarily for her involvement in the 2016 South Korean political scandal, stemming from her influence over the 11th President of South Korea, Park Geun-hye. In 2018, a court sentenced Choi to 20 years of imprisonment on corruption charges.

Democratic Party Rep. Park Chan-dae criticized the presidential office for its silence on the issue, calling it "a serious matter that needs to be uncovered."

“A country ruled by non-elected officials is not normal,” he said, adding, "We have already been through it once and we know how it ended. We will definitely correct the abnormality,” he said.

The government has not made any official comment.

A high-ranking official from the presidential office is reported to have denied the allegations surrounding the presidential couple, saying that Myeong had met Yoon a few times before being inaugurated, but there was no meeting or communication after he took office.

The official also disputed Myeong's claim that he was offered a position on the transition committee and a public office.