Former Seoul Mayor Oh Se-hoon has decided to join the main opposition Liberty Korea Party's leadership race set for February 27th. 

Six of the eight candidates, including Oh, said earlier they would not register their candidacies on Tuesday if the party did not postpone the event to avoid overlapping with the second summit between North Korea and the U.S. slated for February 27th and 28th in Vietnam.

Oh said in a news conference Tuesday that although he still doesn't agree with the party's plan to keep the convention date unchanged, he has decided that he cannot stand by watching the fall of conservatism.

Other candidates including Reps. Chung Woo-taik, Ahn Sang-soo and Shim Jae-cheol issued statements saying that they will not run.  

Another contender, Rep. Joo Ho-young, is likely to announce his decision on Tuesday.

Former Prime Minister Hwang Kyo-ahn and Rep. Kim Jin-tae registered their candidacies Tuesday morning.