Former Democratic Party of Korea (DPK) leader Jung Chung-rae won the party-member primary in the country's southeast Sunday, a day after his narrow loss to rival Kim Min-seok in the central region, as the party leadership race gets into full swing.

Jung beat Kim 46.65 percent to 43.85 percent in the primary vote cast by dues-paying party members in Busan, Ulsan and South Gyeongsang Province, according to party officials.

Their rival and third candidate Song Young-gil garnered 9.5 percent.

With Sunday's win, Jung bounced back from his narrow defeat to Kim in the central Chungcheong region from a day earlier, where Kim edged out Jung 45.05 percent to 44.61 percent.

Jung's Saturday loss was seen as a setback as the Chungcheong region is considered his home turf.

The DPK's leadership race has primarily been a competition between Jung, who has long aligned with the DPK's hard-line wing rather than fully backing President Lee Jae Myung, and Kim, a key political ally of the president.

The DPK is set to hold the national convention Aug. 17 to elect its new leader, who will play a key role in overseeing the nomination of candidates for the April 2028 parliamentary elections.