Regardless of which candidate wins the election in June, he will be tasked with suppressing growing working-class opposition anger amid worsening economic and social conditions.

South Korea's third acting leader in five months, Lee Ju-ho, is an understated labour economist and education bureaucrat thrust into managing high-stakes trade talks with the United States and a country reeling from political knife fights before a crucial election.

Han, who briefly served as acting leader following President Yoon Suk-yeol's impeachment over a controversial martial law declaration, said he would push for constitutional amendments to better balance power between the president and parliament.