South Korea's main opposition Democratic United Party elected a floor leader and an interim leader Friday amid controversy over a behind-the-doors power- sharing deal.

Park Jie-won, a member of the liberal party's supreme council, defeated his rival Yoo Ihn-tae in an internal poll earlier in the day, becoming the latest floor leader and an interim head of the party.

A close confidant to late President Kim Dae-jung, Park leads a faction of those representing South Korea's southwestern province of Jeolla, a traditional liberal stronghold.

Another clique consists of those loyal to late President Roh Moo-hyun, including the party's presidential front-runner Moon Jae-in and the former Prime Minister Lee Hae-chan.

The two factions have copped criticism over an alleged backroom deal in which Park runs for floor leader and Lee for chairmanship in a convention slated for June 9, sharing key posts behind closed doors.

The deal between Park, a Jeolla icon, and Lee, popular in the central Chungcheong provinces, reeks of deep-rooted regionalism as the party tries to woo voters in both regions ahead of the December presidential poll.

Park, who served as a floor leader in 2010-2011, unsuccessfully ran for the party presidency in January.

Han Myeong-sook, who was elected leader at the time, stepped down last month over the party's embarrassing defeat in the April parliamentary elections. Moon Sung-keun, a Roh loyalist, has since led the party.