The party's 18 lawmakers, mostly based in the southwestern region, announced Sunday they will create a new party on Feb. 6 if the integration plan passes through the convention.

They have objected to the "collusion of conservatives," saying it would obscure the party's political identity and irk core supporters in its stronghold of the southwestern Honam region.

A conference of the new party promoters will be held Jan. 28.

The preparatory committee will be headed by Rep. Cho Bae-sook, former chief of the party's policy committee, they said.

The lawmakers, close to the late former President Kim Dae-jung, pledged to advocate a bolder engagement with North Korea and expand welfare policies for ordinary citizens as their new party's key policies.

The People's Party currently holds 39 seats in the 299-member National Assembly. Its merger with the Bareun Party will create a party with 48 parliamentary seats.

Later in the day, People's Party leader Ahn Cheol-soo warned of an "extraordinary" measure against opponents of the merger.

"The opponents are about to cross the line with their extreme actions, including making a party split official. If such a thing happened, as the party's leader, I cannot but take an extraordinary measure," Ahn said during a joint press conference with Bareun Party chief Yoo Seong-min.

Ahn did not specify the special step. When asked whether he means expelling them, he said he does not want to see such a situation occur.

The leaders of the two parties reaffirmed their resolve to reform politics during the press meeting.

"We have declared a clear break from old, anachronistic, corrupt and regionalism-based politics. We promise to become a bona fide democratic party free from regionalism and factionalism," Yoo said. (Yonhap)