Candidate registration began Thursday in the race to select a new leader of the minor opposition People's Party, with former leader Ahn Cheol-soo seeking to regain the reins despite criticism it's too early for him to return, just a few months after his election defeat.

It is expected to be a three-way race with Ahn and two other party heavyweights, Reps. Chung Dong-young and Chun Jung-bae. Ahn and Chung officially registered their bids, while Chun is expected to do so before registration closes Friday.

Another heavyweight, Kim Han-gil, decided against running, raising speculation that he may join with Ahn. The contest could expand if deputy floor leader Lee Un-ju, who had planned to run as Ahn's running mate, decides to join.

The winner will be decided in the party's national convention set for Aug. 27.

All three candidates rallied support in the party's home turf of Honam in the country's southwest.

Ahn visited the city of Gwangju to hold a series of discussions and meetings with party members. After registering his bid, Ahn told reporters, "I believe (party members) will judge who is capable of carrying out reforms and pulling off a victory in local elections" next year.

Chun, a former party co-chair, also visited Gwangju.

"Candidate Ahn failed to live up to Honam's expectations and failed to be chosen," Chun said in a press conference. "I will begin my efforts to help (the party) overcome the crisis and restore public support here in Honam."

Chun strongly denounced Ahn's bid.

"He is a sort of arsonist who put the party into the crisis, but he is seeking to come back to put out the fire," he said, calling Ahn's bid a "serious problem" that makes the party lose further public trust.

Chun said that Ahn should take responsibility for the defeat in May's presidential election and spend time thinking about what went wrong. He also urged party members to show Ahn that there is no future for politicians running against the will of the people.

Chung also called for support, saying the party should shake off the image as Ahn's party.

"Should Chung Dong-young be elected, it will serve as a firm certificate that the People's Party is not Ahn Cheol-soo's party," he said.

Observers say that Chun and Chung could ultimately unify their candidacies to block Ahn's election.

The party has adopted a runoff vote system in the upcoming election, a move seen as more favorable to Ahn's opponents. (Yonhap)