Lawmakers of the main opposition Democratic Party of Korea hold banners urging a special counsel probe into the government's alleged interference in investigations into a Marine's death, during a press conference at the National Assembly in Yeouido, Seoul, Monday. Yonhap

The main opposition Democratic Party of Korea (DPK) is ramping up pressure on President Yoon Suk Yeol to approve a bill proposing a special counsel investigation into the death of a Marine, which has been one of the main sources of bipartisan conflict.

The DPK has alleged that the Yoon administration influenced the military's investigation into the death of Corporal Chae Su-geun, who died last year during a search operation after floods, in order to downplay the responsibilities of ranking military officials.

In a related move, the opposition already introduced a separate bill last month to investigate then-Defense Minister Lee Jong-sup, amid suspicion that Yoon appointed him as ambassador to Australia to shield him from accusations. Lee resigned from the post in late March following mounting criticism, and the controversy over his appointment is believed to be one factor that undermined support for the ruling bloc ahead of the general elections.

During a DPK Supreme Council meeting, Monday, floor leader Rep. Hong Ihk-pyo said the party will do its best to pass the two bills before the 21st National Assembly ends on May 29. After that date, pending bills will be automatically scrapped, as the newly elected lawmakers from last week's general elections will constitute the 22nd Assembly.

"We still have over a month left in the term of the 21st Assembly, and there are a number of pending issues, including special counsel probe bills on Chae's death and (former ambassador) Lee," Hong said. "Through negotiations with the ruling party, we will do our best to address the bills until the very last moment."

The bill on Chae is scheduled for a vote at a plenary session and the bill on Lee is now pending at the Legislation and Judiciary Committee before being presented for a decision in a plenary session.

The DPK is seeking to hold a plenary session on May 2 and pass the bills by taking advantage of its majority status – the DPK and its satellite party hold 156 out of a total 297 seats in the Assembly.

DPK deputy floor leader Rep. Park Ju-min, who proposed the bill on Lee, said during a radio interview with broadcaster MBC that the two measures could be combined in the tabling process.

Then-Ambassador to Australia Lee Jong-sup attends a meeting of ambassadors at the Ministry of Foreign Affairs in Seoul, March 28. Joint Press Corps

The DPK is seeking to expedite the voting for the bills to maintain the momentum of the election results, where the party secured an overwhelming victory.

Interpreting the results as a sign of public distrust in the Yoon administration, the president pledged to "change the approach to governing" and collaborate with the opposition. With these commitments, there is widespread anticipation that Yoon will likely hesitate to exercise his veto power.

If Yoon vetoes the bills and returns them to the Assembly for a second vote, the DPK cannot unilaterally pass them, because a second voting requires approval from two-thirds of attending lawmakers. In that case, the DPK will likely witness those bills being scrapped but can launch political offensives, arguing that Yoon is not demonstrating gestures of cooperation.

Moreover, the bills are gaining support even from some ruling People Power Party (PPP) lawmakers.

PPP Rep. Cho Kyoung-tae said, "It is hard to deny that the Marine's death affected the public sentiment during the general elections." He added, "There is no reason (for me) to oppose the bills."

Kim Jae-sup, who was elected in Seoul's Dobong-A district, also said in a radio interview with broadcaster CBS, Monday, that he is "positive about the special counsel probe on Chae's case," but "the issue should be handled by the 22nd Assembly."

On Monday, the PPP convened a meeting of lawmakers who secured their fourth term or more, aiming to brainstorm ideas to navigate the party through the post-election turmoil. After the election loss, the party's interim leader Han Dong-hoon resigned, leaving the party leadership in a state of uncertainty.

The PPP's acting leader Rep. Yun Jae-ok said, "The party charter states that an emergency committee is required to hold a party convention." But he added, "Nothing has been determined about the next leadership and how to recover from the election loss."