Acting President and Prime Minister Han Duck-soo resigned Thursday citing his need “to take on bigger responsibility,” amid expectations that he would soon announce his intention to run in the presidential election on June 3.

“Respected citizens, I stand here to deliver my decision on an issue that I’ve been deeply deliberating. I have decided to step down from my roles as acting president and prime minister,” Han said in a televised public speech aired in the afternoon.

Though Han did not directly say that he plans to declare presidential candidacy, he said that he has decided “to take on a bigger responsibility by stepping down" from his current role.

The responsibility involves helping South Korea overcome the security and economic risks the export-reliant economy now faces, including the shift in the global trade order, according to Han.

On his last day in office Thursday, Han presided over a ministerial-level meeting on national security issues in the morning of his last day as acting president and prime minister.

At the meeting, Han highlighted the importance of maintaining strong national security to high-ranking security officials, including national security adviser Shin Won-sik and Foreign Minister Cho Tae-yul, while expressing concerns about risks stemming from North Korea’s advancing ties with Russia.

Signs of Han gearing up to declare a bid for the presidency have been reported in recent days, backed by reports of officials from the Prime Minister’s Office and the presidential office joining what would be his election campaign. Son Young-taek, Han’s former chief aide and secretary, were among the officials, reports said.

Han’s team has reportedly set up a campaign office in Yeouido, western Seoul.

Finance Minister Choi Sang-mok, who was the country’s acting president and acting prime minister from Dec. 27 to March 24, when Han was impeached and suspended from his duties by the opposition-led National Assembly, will assume the role of acting president as required by law.

Han is expected to declare his candidacy Friday.

The main liberal Democratic Party of Korea denounced Han Duck-soo’s potential bid for presidency as a selfish move selling out national interests. Rep. Kim Min-seok, who is on the Democratic Party's Supreme Council, said that Han "finally revealed his true intentions” during a press briefing held in front of the Government Complex Seoul.

Kim pointed to the recent mass resignation of Han’s aides, calling Han’s likely candidacy a plan engineered through "abusing” his power as a public servant to prepare for election, which is subject to criminal punishment.

Han’s potential presidential bid could push the remaining two contenders vying for the conservative People Power Party’s nomination for the presidential election to throw in their towel to back Han Duck-soo as their candidate, observers say. Han could either enter the presidential race as an independent conservative candidate or partner up with the winner of the People Power Party’s ongoing primary race. With former People Power Party Chair Han Dong-hoon and ex-Labor Minister Kim Moon-soo competing for the party’s nomination, the winner will be announced during party convention scheduled for Saturday.

In a survey jointly conducted by Korea Research and three other firms, asking respondents of “who is the most appropriate to become the next president,” Han Duck-soo ranked No. 2 with 13 percent, trailing behind Democratic Party candidate Lee Jae-myung, who saw 42 percent. Han Dong-hoon saw 9 percent, while Kim Moon-soo saw 6 percent. The survey released Thursday involved 1,000 respondents aged 18 or older.

Han Duck-soo, 75, is a career technocrat, who served as prime minister under former President Yoon since May 2022. He has held the prime minister’s office twice, as he previously held the role from April 2007 to February 2008, under the former Roh Moo-hyun administration.

He has served in key leadership positions under five different presidents. Besides prime minister, his roles have ranged from ambassador to the United States, finance minister, trade minister, presidential secretary for policy coordination and ambassador to the OECD.

Han studied economics at Seoul National University, earning his masters and doctorate in economics from Harvard University.