Acting President and Prime Minister Han Duck-soo speaks to reporters at the Government Complex in Seoul, Sunday. Yonhap

Prime Minister Han Duck-soo, who has assumed the role of acting president following the impeachment of President Yoon Suk Yeol on Saturday, is a career bureaucrat with a background in economics who has spent 40 years as a public servant.

Known for his nonpartisan approach and meticulous working style, Han is widely regarded as a stabilizing figure during a time of unprecedented political uncertainty.

Born in 1946 in Jeonju, North Jeolla Province, Han graduated from Seoul National University and later earned a Ph.D. in economics from Harvard University. He began his career as a customs officer after passing the civil service exam in 1970 and has since held nearly every key government position.

Han's career has been marked by his ability to work efficiently across political lines, serving under both liberal and conservative administrations.

During the liberal Kim Dae-jung administration (1998-2003), he served as minister for trade in the former Ministry of Foreign Affairs and Trade in 1998. In the latter part of Kim's term, Han served as the senior presidential secretary for economic affairs.

During the 2003-08 Roh Moo-hyun administration, he played a pivotal role in negotiating the Korea-U.S. Free Trade Agreement in 2006 and was later appointed prime minister in 2007.

Han continued to demonstrate his expertise under the conservative Lee Myung-bak administration, serving as Korea's ambassador to the United States, and later as chairman of the Korea International Trade Association.

In 2022, he returned to the role of prime minister under Yoon, becoming the longest-serving prime minister since Korea's democratization in 1987.

Throughout his latest tenure, Han has been credited with focusing on domestic affairs, thereby counterbalancing Yoon's emphasis on foreign policy. His seasoned leadership has been particularly evident during national crises, such as his management of controversies surrounding the World Scout Jamboree in 2023 and the release of contaminated water from Fukushima.

With Yoon's duties officially suspended as of 7:24 p.m., Saturday, Han assumed full presidential powers, including commanding the Armed Forces, ratifying treaties and exercising legislative vetoes. Political observers expect him to draw on his decades of expertise to address pressing issues in national defense, diplomacy and the economy.

Yet, Han's time as acting president is unlikely to be smooth.

He faces critical decisions, such as whether to veto opposition-led bills, including the special prosecution bill targeting first lady Kim Keon Hee.

Han himself is also under investigation by both an opposition-led special counsel and the National Police Agency. The opposition accuses Han of colluding with Yoon, citing his presence at a Cabinet meeting held shortly before Yoon declared martial law.

Despite mounting challenges, Han vowed to fulfill his duties with unwavering commitment. At his first Cabinet meeting as acting president, he vowed to "take full responsibility" and ensure "there will be no vacuum in state affairs."