South Korean President Yoon Suk Yeol promised "reform" and the head of his ruling party resigned on Thursday after a disastrous election increased the opposition's stranglehold on parliament.
In addition to People Power Party (PPP) leader Han Dong-hoon, Prime Minister Han Duck-soo and a string of senior aides also offered to step down, local media said.
The result sets the stage for a legislative stalemate over President Yoon's remaining three years in office, just as the country faces challenges including a weak economy and an increasingly aggressive North Korea.
"I will humbly honour the will of the people expressed in the general election, reform the state affairs, and do my best to stabilise the economy and people's livelihood," Yoon said, according to his chief of staff Lee Kwan-sup.
Near final results from Wednesday's vote showed Yoon's conservative People Power Party (PPP) and its satellite sliding from 114 seats in parliament to just 108, according to National Election Commission figures.
The big winners were Lee Jae-myung's Democratic Party (DP) and its partner, which saw their seat tally rise to 174 from 156 in the outgoing legislature.
The newly-founded Rebuilding Korea party, led by former justice minister Cho Kuk, capitalised on discontent with the two main parties to pick up 12 seats.
The landslide was however less emphatic than suggested by exit polls, with all opposition parties combined falling short of a super-majority of 200 seats in the 300-strong National Assembly.
South Korea uses a mix of first-past-the-post seats and proportional representation and has one legislative chamber. Presidents can serve only one five-year term.
The big winner is Lee, 60, who narrowly lost a presidential election to Yoon in 2022 and in January was stabbed in the neck on the campaign trail.
"This isn't the Democratic Party's victory but a great victory for the people," the former factory worker said Thursday morning.
"Politicians on both sides of the aisle must pool our strength to deal with the current economic crisis. The Democratic Party will lead the way in solving the livelihood crisis," he told reporters.
He has won support for policies including cash handouts to young adults, free school uniforms and maternity care.
He may now have another shot at the top job.
"With this outcome, he has become the most powerful MP with the presidential run approaching," political pundit Yoo Jung-hoon told AFP.
But critics call the former human rights lawyer a populist and point to a string of corruption allegations hanging over him that he has dismissed as politically motivated.
Yoon has taken a tough line with the nuclear-armed North while improving ties with Washington and former colonial occupier Japan.
But the PPP's lack of control of the National Assembly has stymied his legislative agenda.
This includes planned healthcare reforms -- that are backed by voters but have sparked a crippling strike by doctors -- and a pledge to abolish the ministry of gender equality.
The election results represent Yoon's "biggest political crisis" since he took power, the conservative daily newspaper Chosun Ilbo said.
Analysts said Wednesday's vote reflected frustration that the government had failed to deal with inequality, sky-high housing prices and youth unemployment in the nation of 51 million people.
The opposition also hammered Yoon after he called the price of green onions, a staple in Korean cooking, "reasonable" and footage of his wife showed her accepting a $2,200 designer handbag.
"The election is a stern warning from the public that will force Yoon to change direction and cooperate with the opposition unless he wishes to become a lame duck for the rest of his term," Chae Jin-won of Humanitas College at Kyung Hee University told AFP.
Even though the opposition missed out on a supermajority -- two-thirds control of the parliament would have allowed them to try and impeach Yoon -- the president remains in a precarious position, he said.
If Yoon can't find a way to work with the opposition, there is a "likelihood of impeachment, which some factions in the ruling party may comply with for the sake of their own political futures."
