Kim Moon-soo, formerly labor minister in the Yoon Suk Yeol administration, officially registered Sunday as the People Power Party’s presidential candidate for the June 3 election — clinching the nomination after days of internal strife and pressure to step aside for former Prime Minister and two-time acting President Han Duck-soo.

Kim’s rise as the conservative standard-bearer against Lee Jae-myung, the candidate for the liberal Democratic Party of Korea, marks a striking political turn for someone who was once a champion of South Korea’s pro-democracy and liberal labor movements in his early years.

Kim was born in 1951 in Yeongcheon, North Gyeongsang Province, and first drew public attention in 1969 as a high school senior, leading a protest against then-President Park Chung-hee’s push to amend the Constitution to allow for a third term. The protest earned Kim a suspension from school, but marked the beginning of a political life defined by defiance.

Kim entered Seoul National University’s business school in 1970 and soon joined a student circle focused on issues concerning labor and democratization. Deeply moved by the self-immolation of labor activist Jeon Tae-il, Kim left the classroom behind for the factory floor.

He took jobs under assumed names at industrial sites, including garment and dyeing factories, in Seoul and Incheon — not just to observe, but to organize from within. He eventually rose to lead the labor union at Hanil Doruko, a major metal company.

By the 1980s, Kim had become a household name among activists.

As a key figure in the Seoul Region Labor Movement Alliance, Kim helped lead strikes and worker protests during a period of heavy surveillance and state repression under military dictator Chun Doo-hwan. In 1986, Kim was arrested, tortured and almost lost hearing in one ear after electric shock interrogations. Yet, he refused to disclose the identities of fellow activists like Sim Sang-jung and Rhyu Si-min, both of whom would go on to become prominent progressive politicians.

Kim's unwavering silence became a symbol of his character. Even as South Korea transitioned to democracy after 1987 and former dissidents entered electoral politics, Kim’s principles remained steeped in his past.

In 1990, amid the fragmentation of liberal opposition forces ahead of the 1992 presidential election and growing concerns that labor interests were being sidelined, Kim helped establish the Minjung Party, a progressive platform aimed at giving workers a political voice.

But the party struggled to gain public support. After its disappointing performance in both the general and presidential elections of 1992, Kim acknowledged the failure and disbanded the party. He stepped away from politics, taking up work as a taxi driver.

Kim’s return to politics came through an unexpected door and marked a turning point in his ideological journey.

In 1994, then-President Kim Young-sam, himself a former opposition leader, sought to broaden the ruling Democratic Liberal Party -- which later became the Grand National Party, a predecessor of the current People Power Party -- by bringing in figures from the democratization movement.

Kim Moon-soo accepted the offer and thus crossed the ideological divide. His decision drew harsh criticism from former fellow travelers in the labor movement, some branding him a “turncoat.”

At the time, Kim was quoted as saying, “The era of revolution is over” — a remark widely seen as signaling his embrace of political pragmatism amid change.

Kim went on to serve three consecutive terms in the National Assembly, representing Bucheon, Gyeonggi Province. In 2006, he was elected governor of Gyeonggi Province, where he began the development of major infrastructure projects, including the GTX high-speed rail and regional bus systems.

However, his influence waned in the 2010s, following a string of political failures.

It was not until the Yoon Suk Yeol administration that Kim made his comeback. He was appointed chair of the minister-level Economic, Social and Labor Council in 2022. Later in 2024, he was named labor minister despite strong opposition in the National Assembly.

Kim further grabbed the spotlight for his opposition of Yoon's impeachment following the botched martial law declaration on Dec. 3, 2024.

When the National Assembly demanded a formal apology over the martial law debacle later that month, all the other Cabinet members stood and bowed in apology. Kim did not. His refusal set him apart and sparked speculation of a presidential run following Yoon’s eventual impeachment and removal from office.

On April 8, Kim resigned from the Cabinet and declared his candidacy.

Kim went on to win the People Power Party nomination, defeating former party Chair Han Dong-hoon and veteran lawmaker Hong Joon-pyo, among other high-profile figures. Running under the slogan “Unite against Lee Jae-myung,” Kim emphasized the need to consolidate the right, particularly with Han Duck-soo, who was widely viewed at the time as a strong potential presidential contender.

Just as Kim was set to clinch the party's nomination, Han Duck-soo declared his independent candidacy, triggering an internal crisis within the People Power Party to unite the conservative bloc. The party's leadership attempted to replace Kim with Han, but Kim held his ground, stating: “I, Kim Moon-soo, am the legitimate nominee who can beat Lee Jae-myung.”

To some, Kim Moon-soo’s defiance in the face of pressure from the People Power Party has cemented his image as an icon of political endurance.

After his official registration as the People Power Party's presidential candidate on Sunday, Kim said, “It’s time to set aside our differences and focus on unity and reconciliation.”