Supporters of arrested and impeached South Korean President Yoon Suk-yeol wave the national flags as they gather outside the Seoul Detention Center in Uiwang, South Korea, on March 7, 2025. Photo: VCG

South Korea's opposition parties on Friday submitted an impeachment motion against Choi Sang-mok, deputy prime minister for economic affairs who became acting president in December last year following the impeachments of both president and prime minister, according to the Xinhua News Agency. 

The main liberal opposition Democratic Party and four other minor parties submitted the impeachment motion for four reasons, including Choi's alleged involvement in the impeached President Yoon Suk-yeol's botched martial law imposition and his refusal to appoint a constitutional court justice for over three weeks. Because of Choi's appointment refusal, the nine-member constitutional court currently has eight justices, according to Xinhua. 

In late December, Choi appointed two justices to the court but held off on the appointment of opposition-recommended Justice candidate Ma Eun-hyuk, citing the need for a bipartisan consensus, according to the Yonhap News Agency. 

Zhan Debin, director and professor of the Center for Korean Peninsula Studies at the Shanghai University of International Business and Economics, said that opposition parties have been considering an impeachment motion against Choi largely because of his refusal to appoint Ma, as his appointment may significantly increase the chances of Yoon being removed from office.  

Zhan also noted that during his time as acting president, Choi vetoed several special investigation bills seen as crucial to advancing probes into Yoon.

However, bringing forward an impeachment motion does not guarantee its success, as it remains part of a broader political contest. And in the coming week, South Korea could see a sharp escalation in political tension, potentially marking a watershed moment for South Korea's political landscape in the months or even years to come, Zhan noted.

Yonhap reported that the impeachment motion against Choi came just days before the Constitutional Court is set to rule on Prime Minister Han Duck-soo's impeachment, scheduled for March 24. A ruling date has yet to be set for President Yoon's case.

The timing may also influence the legal fate of Democratic Party leader Lee Jae-myung, whose appellate court verdict on charges of violating the Public Official Election Act is due on March 26, according to The Chosun Daily. Lee was indicted without detention in September 2022 for allegedly making false statements during the election campaign.

Zhan noted that the Democratic Party's sense of urgency has deepened following Yoon's release on March 8. Moving forward with repeated impeachment attempts against the acting president could spark public backlash, while choosing inaction risks alienating the party's support base — leaving the party caught between two unfavorable options, the expert said.

Meanwhile, the ruling People Power Party is also eager to manage the fallout from Yoon's martial law controversy and the ongoing impeachment trials, as both have implications for its public approval ratings.