Second-generation politician debuted as 'economic mentor' to Lee Hoi-chang
Former chief of staff to Park Geun-hye but later became political enemies
The presidential nominee of the conservative Bareun Party is a four-term lawmaker known for his complicated ties to ousted President Park Geun-hye.
Yoo Seong-min, 59, entered the National Assembly in 2004 on the proportional representation ticket of the conservative Grand National Party.
He served as chief aide to then party chief Park, and in 2007, helped prepare her for the presidential primary against Lee Myung-bak. Park lost to Lee.
During the 2012 presidential election, the former economist was one of the key architects of Park's "economic democratization" policies, which called for tighter control of unfair practices of large businesses and expanded spending on welfare for low-income citizens.
But he was critical of her campaign pledge to achieve the welfare expansion without increasing taxes.
In 2015, Yoo was elected floor leader of Park's then-ruling Saenuri Party. By then, he was a three-term lawmaker representing the southeastern city of Daegu, Park's hometown.
He clashed with Park as she failed to fulfill her pledges of inclusive policies. He openly criticized Park for resorting to her close aides while ignoring democratic procedures in both the government and the ruling party.
Park responded with an angry call for judgment on "politics of betrayal," and then he resigned as floor leader.
The political bigwig even failed to win his party's nomination for the parliamentary elections in 2016. But he won re-election in Daegu as an independent and later returned to the party.
Long sidelined from the mainstream, Yoo made a comeback to the center of party politics in the wake of a corruption scandal that implicated Park and led to her dismissal earlier this month. The incident vindicated Yoo as a brave politician who spoke his mind to the powerful leader even risking being estranged.
Yoo bolted from the Saenuri Party with 32 other lawmakers and formed the Bareun Party.
He received a bachelor's degree from Seoul National University and a master's and doctorate from the University of Wisconsin-Madison.