President-elect Yoon Suk-yeol has tapped former Prime Minister Han Duck-soo to join his administration as prime minister, a personnel pick believed to help Yoon exert influence as he takes charge of a minority government in May.

In a press conference held Sunday afternoon, Yoon said Han was chosen as he has served in various key positions "regardless of political allegiance but only due to his competence and expertise."

"The new government is tasked with setting a foundation for a new leap for our economy in a serious environment and thoroughly preparing for an era where economy and security are combined as a single factor," Yoon said in announcing his nomination.

"I believe nominee Han Duck-soo is the right person to oversee and coordinate the Cabinet and carry out state affairs based on his abundant experience in both public and private sectors."

The 72-year-old trade and diplomacy expert has been touted for days as the most likely candidate to serve as prime minister, with a focus on rebuilding the economy while promoting cooperation and unity between rival parties.

Han has served in key posts in both left- and right-leaning administrations, and is considered a strong figure to contribute to Yoon’s initiative to form a coalition government.

He served as prime minister during the liberal Roh Moo-hyun administration from April 2007 to February 2008 and later served as ambassador to the United States from 2009 to 2012 for the conservative Lee Myung-bak administration.

Born in Jeonju, North Jeolla Province, Han graduated from Seoul National University in 1971 with a degree in economics, and went on to earn his masters and doctorate in economics at Harvard University.

He entered the public sector by passing the state-run public officer qualification exam in 1970, and spent the early years of his career in the Korea Customs Service working with a number of key government agencies, including the presidential office.

Until being chosen to serve for a second time as prime minister, Han had been serving in teaching positions at Hongik University and Dankook University. He is favored by many for his extensive career in economics as well as broad expertise in diplomacy.

Han served as the 11th commissioner of the Korean Intellectual Property Office from December 1996 to March 1997 and then was named vice industry minister for a year until March 1998. He also played a key role in negotiating the free trade agreement with the US.

His background is expected to help him easily pass the nomination hearing at the parliament, where the liberal Democratic Party of Korea controls 172 out of 300 legislator seats. Han experienced no trouble in passing the same hearing in 2007 for the Roh administration.

The nomination was announced Sunday so that the entire appointment procedure could be completed before his administration officially kicks off in May.

"I am honored but also feel huge responsibility to be nominate for the seat of prime minister in this very serious situation surrounding South Korea's economy and geography," Han said in accepting the nomination.

For South Korea to succeed in the long term, the nominee said the country has to enhance its defense capabilities and improve its financial stability while working to secure more foreign currency and keep its productivity high.

He said the country would be forced to increase fiscal spending in the coming years, but South Korea has to concurrently make efforts to improve its financial standing if it wants to build international trust and stability.

The government should also be prepared to tackle inequality while improving transparency and unity among different groups to ensure productivity stays high and key policies directly related to individuals' level of happiness are positively reinforced, he added.

"As the newly nominated prime minister, I will assist President Yoon Suk-yeol to create policies from the administrative branch that are drafted through constant discussions and communications," Han said.

"I believe cooperation and unity are key factors of bringing success to these policies."

Han will be working with Yoon to pick nominees for key ministerial posts in coming weeks, and they are focused in identifying candidates to lead the Ministry of Economy and Finance and serve as the deputy prime minister for economy.

Yim Jong-ryong, former head of the Financial Services Commission, was rumored be heading the Finance Ministry, but Han said Yim rejected the offer to join for personal reasons.

Unlike in the past where presidents assumed the greatest power in the administrative branch whereas prime minister work to assist the initiatives of their presidents, Yoon has repeatedly vowed to divide his power to others in the administration, mainly to whoever serves as the prime minister.

Han will have greater influence than other prime ministers in the past if the promise is fulfilled.