Rep. Lee Jung-hyun said that should he be elected, it would mark a "touching" case of overcoming regionalism. Lee is from the country's southwestern Honam region where liberal opposition parties have traditionally held greater sway.

"(If I get elected,) I would turn the party into one that serves for citizens, and bring about a change in South Korea's politics as well," he told Yonhap News Agency over the phone.

Rep. Joo stressed the importance of reforming the party in a direction that promotes unity so as to win in next year's presidential election.

"I am the one fit for (the task of) promoting party unity," he said.

Rep. Lee Joo-young also underscored that the party should make concerted efforts to overcome factional feuds and unite as one.

Han, whose constituency is in Yongin just south of Seoul, cast himself as the most suitable candidate to push for the party's personnel reform, emphasizing that he is not affiliated with any party faction.

For four Supreme Council seats, eight candidates have been competing. They are Cho Won-jin, Lee Jang-woo, Ham Jin-kyu, Kang Seok-ho, Jeong Yong-gi, Chung Moon-hun. Lee Eun-jae and Choi Yeon-hye.

Yoo Chang-soo and Lee Boo-hyeong are vying for one council seat allotted for a youth party member.

Meanwhile, the main opposition Minjoo Party of Korea is set to hold its own leadership election on Aug. 27. (Yonhap)