After the National Assembly failed to pass the motion to impeach South Korean President Yoon Suk Yeol on Saturday, Prime Minister Han Duck-soo vowed Sunday morning to “humbly seek cooperation” with the ruling People Power Party to “ensure all state functions operate smoothly and stably.”

However, the opposing Democratic Party of Korea denounced such plans, claiming that such measures are “unconstitutional.”

According to the Constitution, the prime minister is only allowed to assume the role of interim leader due to circumstances where the president is unable to fulfill their duties due to reasons such as death, resignation or impeachment.

“Despite such a consensus between Yoon, the prime minister and the People Power Party leader Han, such an unconstitutional way of governing is not allowed, even for a minute,” said Rep. Kim Min-seok of the Democratic Party of Korea. “Han does not hold legitimate authority to serve as a leader in the current situation.”

National Assembly Speaker Woo Won-shik also stated that it would be a “blatant violation of the Constitution” if the prime minister and the ruling party jointly exercised presidential power.

Denouncing the joint press briefing as “arrogant,” Woo stated: “The transfer of presidential power comes from the people, and such a process should abide by the Constitution and the principle of popular sovereignty.”

Some opposition figures have also claimed the prime minister should also be held responsible for the martial law declaration, as Han’s exact role in the process behind the martial law declaration remains unclear.

According to local media reports, though Han reportedly tried to dissuade the president before martial law was declared, Yoon pushed ahead with the plan. Han has never come forth to address such claims himself, and according to a widely held view, Han cannot avoid responsibility for failing to prevent the declaration of martial law as the head of the Cabinet.

After graduating with a master’s degree in public administration from Harvard University, Han built a career as a government official, primarily focused on economic and diplomatic affairs.

Han is also recognized for his political neutrality, having served under multiple administrations with differing political ideologies.

During the Kim Dae-jung administration, recognized for its liberal ideology, Han served as the senior presidential secretary for economic affairs from 2001 to 2002. During the Roh Moo-hyun administration, another liberal government, Han served as prime minister from 2007 to 2008.

In conservative governments, Han served as Korea’s Ambassador to the United States during the Lee Myung-bak administration from 2009 to 2012. Yoon appointed him prime minister after he was elected in 2022.