Acting President Han Duck-soo attends a meeting with senior government and ruling party officials at his official residence in Seoul, Friday. Yonhap

Acting President Han Duck-soo and the main opposition Democratic Party of Korea (DPK) are facing dilemmas in their power struggles for an upper hand in key state affairs amid the absence of President Yoon Suk Yeol, according to political analysts, Sunday.

In the coming days, Han must decide whether to veto two special investigation bills: one targeting first lady Kim Keon Hee and another probing Yoon's failed martial law declaration. Both bills pose serious challenges to the faltering Yoon administration.

The DPK, which holds a parliamentary majority, has threatened to impeach Han if he does not approve the bills. The party issued an ultimatum, Sunday, stating that Han will have to "bear responsibility" if he fails to make a decision by Christmas Eve.

However, whether the DPK will follow through on its threat remains uncertain, as excessive power plays could backfire. The fact that Han, as acting president, has the authority to appoint Constitutional Court justices — a key issue for the DPK — complicates the opposition's strategy.

Rep. Park Chan-dae, left, floor leader of the main opposition Democratic Party of Korea (DPK), speaks during a press conference at the National Assembly in Seoul, Sunday. Yonhap

Han has two weeks to decide on the special probe bills after the opposition-controlled National Assembly passed on Dec. 12, just two days before approving Yoon's impeachment motion. Han's office said it will carefully review the bills and deliberate before making a decision by the legal deadline of Jan. 1.

As Han was widely regarded as a technocrat rather than a politician, DPK members had initially hoped that the acting president might cooperate in approving the contentious bills. However, Han's rejection of six opposition-backed bills last week has raised doubts about these expectations.

During a Cabinet meeting on Thursday, the acting president vetoed four agricultural bills, the National Assembly Act, and the National Assembly Testimony Appraisal Act, citing constitutional concerns and potential harm to the nation's future.

The vetoes, a rare move from an interim leader, prompted strong backlash from the DPK, which accused Han of "infringing on legislative power" and warned him not to turn the Cabinet into "Yoon Suk Yeol 2.0."

Analysts believe Han faces a tougher decision regarding the special counsel bills, as approving or rejecting them carries significant political consequences.

"It's a major dilemma for the acting president. Public opinion strongly favors a special probe into the first lady, especially since many remain suspicious after prosecutors cleared her of all charges. Han is well aware of this. Additionally, since Han himself acknowledged his failure to stop Yoon from declaring martial law, rejecting the special probe bills into the martial law would seem contradictory," said political commentator Park Sang-byung.

Approving the bills, however, would deal a heavy blow to the ruling People Power Party (PPP) and the embattled president. A special counsel investigation into Yoon and his wife could further weaken the conservatives' position, as they grapple with the fallout from the president's impeachment.

Rep. Kweon Seong-dong, acting leader of the ruling People Power Party, speaks during a press conference at the National Assembly in Seoul, Sunday. Yonhap

PPP acting leader Rep. Kweon Seong-dong criticized the DPK's push for special probes, accusing the opposition of attempting to "paralyze the government and the ruling party." He urged the acting president to exercise his veto powers.

"Failing to use the veto would itself be a violation of the Constitution, given the unconstitutional elements of these bills," Kweon said at a press conference, Sunday.

Meanwhile, the DPK has set a Christmas Eve deadline for Han to approve the bills.

"If Han does not approve the special counsel bill by Dec. 24, we will immediately hold him accountable," said DPK floor leader Rep. Park Chan-dae.

Although Park did not specify how, the opposition bloc has threatened to remove the acting president from office.

With its 170 seats in the 300-member Assembly, the DPK has enough votes to proceed with Han's impeachment on its own, which requires the approval of a parliamentary majority. However, this carries significant political risks for the DPK.

"For the DPK, the top priority is increasing the chances of Yoon's impeachment being upheld by the Constitutional Court. To achieve this, they need cooperation from Han," Park, the political commentator, said.

People hold a rally calling for President Yoon Suk Yeol's impeachment at the May 18 Democracy Square in Gwangju, Saturday. Yonhap

The opposition is pushing for the swift confirmation of nominees to fill three vacancies on the nine-member Constitutional Court, which would increase the chances of upholding Yoon's impeachment.

Under the Constitution, at least six justices must consent to uphold impeachment. While the court can technically proceed with its current six members, a full bench would provide a better chance, as the ruling could still be upheld even if one or two justices dissent.

As acting president, Han has the authority to approve the appointment of judge nominees.

The DPK plans to hold confirmation hearings for two of the nominees on Monday and Tuesday, with expectations that the appointments will be finalized by the end of this year.

However, if the DPK proceeds with Han's impeachment, it risks disrupting its own strategy.

If Han is ousted, Deputy Prime Minister and Finance Minister Choi Sang-mok would step in as interim leader. But this scenario brings even more uncertainties, as Choi has already expressed his willingness to resign following the martial law fallout.