SEOUL - He was young and brash, defying the image of a conservative-leaning politician in South Korea.

Harvard graduate Lee Jun-seok's political debut at age 26 in 2011 as the youngest member of the leadership council of the main conservative party took many by surprise.

Looking out of place alongside veteran politicians, some old enough to be his grandfather, the science whiz had pledged in front of the media to "speak out and work to create real policies... from my own experience and passion".

He was handpicked by the party's then leader, Park Geun-hye, who went on to become South Korea's first female president but was impeached in 2017 due to a massive corruption and influence-peddling scandal.

She had hoped that Mr Lee, a start-up founder, could help the party win the hearts of young voters, but he failed to win any of the three parliamentary elections that he contested in.

Now 36, Mr Lee is hogging the media limelight again after being elected as the youngest leader of the dominant conservative party, which is now called People Power Party (PPP) after several name changes, and is the country's main opposition party.

Political scientist Kim Jae-chun of Sogang University said Mr Lee's election was a "foregone conclusion" as he appealed to the majority of voters in their 20s and 30s who are discontented by President Moon Jae-in's "ill-conceived policies in economics, real estate and even North Korea".

Professor Kim watched Mr Lee's four speeches on the campaign trail and found them "remarkable".

"He's a bright guy, very good at debating," Prof Kim told The Straits Times. "He presented his ideas well and portrayed himself as a representative of the younger generation."

As a child, Mr Lee reportedly lived in Indonesia and Singapore with his father, who worked in a securities company and was posted there for work.

He studied at the elite Seoul Science High School for gifted students before going to Harvard University, where he graduated with a bachelor's degree in economics and computer science.

He was running a tech start-up focused on education in 2011 when he was recruited by Park.

While he never won any parliamentary election, he became a TV celebrity known for his quick wit after joining the reality game show The Genius in 2013.

Mr Lee, who is single, released the book Fair Competition in 2019, sharing his views on key national issues such as gender inequality, economy, education and North Korea.

He was most known for lashing out at radical feminist groups for inflicting "toxic damage" on men, winning male fans who felt they were disadvantaged by the Moon administration's pro-feminist policies.

"The activists destroy those men until they are unable to recover from the damage," Mr Lee wrote. "I wonder how they are different from the terrorists who committed the Sept 11 attacks. Both pose a threat to society as they try to justify their ill-minded causes at the expense of others."

He also revealed his mixed feelings towards Park, who has been in prison since 2017, serving a 20-year jail term for power abuse and other charges.

While grateful to her for introducing him to politics, he said he supported her impeachment as he was "frustrated and disappointed in her after she was sworn in as president".