Former lawmaker and veteran politician Kim Young-sun, a central figure in allegations that President Yoon Suk Yeol meddled in the June 2022 by-elections, denied accusations that she paid for Yoon's political forecasting and alleged poll manipulation expenses in exchange for the ruling party's nomination to run for her seat in the National Assembly.

The prosecution interrogated Kim on Sunday regarding what they consider a violation of the Political Funds Act, namely Kim's wiring of a combined 90 million won ($65,200) in several installments since August 2022 to Myung Tae-kyun, Yoon's former political consultant who ran an election polling and forecasting company.

Kim, however, told reporters that she had nothing to do with the ruling People Power Party's candidate nomination process, and claimed she had no idea about Yoon's election forecasting and alleged poll manipulation expenses until she learned about them on the news, when she appeared at the Changwon District Prosecutors Office in Changwon, South Gyeongsang Province, for questioning.

News of the election interference scandal broke Thursday as the main opposition Democratic Party of Korea accused Yoon of favoritism based on a recorded phone call between Yoon and Myung suggesting Yoon had insisted to Rep. Yoon Sang-hyun -- who was in charge of the party's candidate nomination process at the time -- that Kim be the party's candidate in the June 2022 parliamentary by-election for a National Assembly seat representing a constituency in Changwon, South Gyeongsang Province, which is considered a conservative stronghold.

In response, Myung said he would "never forget (Yoon's) kindness," indicating that Myung had likely asked him for Kim to be nominated as the candidate for that seat. Kim won the by-election and served out her fifth term as a lawmaker until May this year.

The main opposition party claimed that the phone call, made on May 9, 2022, shows evidence of presidential interference in the election process, arguing that although Yoon was then only the president-elect, the nomination of Kim as the ruling People Power Party's candidate was announced on May 10, 2022 -- the day Yoon was inaugurated as president.

Following the revelation of the phone call, Yoon's approval rating sank below the 20 percent threshold, hitting a new low of 19 percent in the final week of October, according to a poll by Gallup Korea on Friday.

On the same day, Yoon's Chief of Staff Chung Jin-suk claimed that Yoon had cut off his relationship with Myung in November 2021, when the presidential nominee selection process drew to a close. Chung also said at the parliamentary audit of the presidential office that Yoon's controversial phone call with Myung on May 9, 2022 had been meant merely as "a word of encouragement."

With the release of the recording, the Democratic Party has ramped up the pressure on the Yoon administration.

Rep. Park Chan-dae, floor leader of the Democratic Party, told reporters Sunday that an investigation of Yoon's wife, Kim Keon Hee, via special counsel is the only way to prevent the Yoon administration's collapse. Yoon has twice vetoed opposition-sponsored bills for such an investigation.

A series of private Telegram messages between first lady Kim and Myung this past February, disclosed by local media JTBC Oct. 2, showed that Yoon's wife was aware that Myung was an intermediary seeking to help Kim Young-sun land the nomination to run for a sixth term in this year's April general election.

This revelation triggered speculations that Yoon's wife may have interfered in the ruling party's candidate nomination process for the April general election -- which the ruling party lost. In that election however, Kim Young-sun was not nominated to run for a sixth term.

On Saturday, an estimated 300,000 people rallied near Seoul Station to demand that Yoon and Kim be investigated for their alleged election meddling, hosted by the main opposition party. Rep. Lee Jae-myung, chair of the Democratic Party, blasted Yoon for his "abuse of power in the pursuit of personal benefits and suppression of his political enemies."