Fifteen lawmakers have decided to leave the center-left People's Party in protest against its leader Ahn Cheol-soo's push for a merger with the center-right Bareun Party, party officials said Monday.

The renegades, including Reps. Chun Jung-bae, Chung Dong-young and Cho Bae-sook, will launch their own new party, named the Party for Democracy and Peace, on Tuesday.

Their defections will reduce the number of People's Party lawmakers to 24.

Three proportional representative lawmakers -- Reps. Lee Sang-don, Chang Jung-sook and Park Joo-hyun -- have also decided to quit the party, but Ahn refuses to expel them. Should they leave the party without being expelled, they will lose their status as lawmakers.

Ahn has been pushing for the merger to forge a new centrist party strong enough to take on the two major parties -- the ruling Democratic Party and main opposition Liberty Korea Party -- ahead of the June gubernatorial and mayoral elections.

But dissenters within his party have opposed the merger plan, citing the parties' different ideological roots and policy stances, particularly on how to handle an increasingly provocative North Korea.

Last month, Ahn and Yoo Seong-min, the leader of the Bareun Party, declared their resolve to merge the parties, vowing to break with "old, corrupt, factional and outmoded" politics and bring together "reform-minded conservatives and rational centrists." (Yonhap)