Floor leader Joo Ho-young will also join them after the party concludes its leadership contest scheduled for next Monday.
Their defections, if finalized, will reduce the number of the embattled party's legislators to 11 and strip it of its status as a parliamentary negotiating bloc, which requires at least 20 lawmakers of the 299-member National Assembly.
"Today, we will embark on a path of grand conservative unity," the lawmakers said in a joint statement. "We will strive for a grand integration to unite all conservative forces to fend off the surge in populism by the Moon Jae-in government and the escalation of the security crisis."
|Joo Ho-young, the floor leader of the minor opposition Bareun Party (Yonhap)|
The lawmakers also voiced their dismay at the Bareun Party's unfruitful efforts to position itself as a promising conservative alternative to the LKP.
"(The party) has tried to be a center of new conservatism, but the Bareun Party has failed to win overwhelming support from citizens," they said. "As a result, what we have been left with is conservatives' division and ensuing responsibilities."
The lawmakers plan to submit to the Bareun Party their written notifications for defection Wednesday and take formal steps to join the LKP the following day.
They include Reps. Kim Moo-sung, Kim Young-woo, Kang Ghil-boo, Kim Yong-tae and Hwang Young-cheul.
On Sunday, party lawmakers held a meeting in last-ditch effort to reconcile their differences over the merger issue but failed to reach any agreement.
The announcement came three days after the LKP decided to expel corruption-tainted former President Park Geun-hye, a step that some Bareun Party members had demanded as a precondition for any tie-up with the LKP.
The minor party splintered off from the LKP late last year amid a factional dispute over the massive corruption scandal involving Park and her longtime friend Choi Soon-sil.
Those who want to remain in the Bareun Party still view the LKP as an outdated old guard tainted by the disgraced former leader, and they stress the need to focus on creating "transparent, reformist" conservative forces.
Shortly before the announcement on the defections, three contenders dropped out of the Bareun Party's leadership race, hoping that their withdrawal could create the momentum for party unity. Their exit leaves Reps. Yoo Seong-min and Ha Tae-kyeung and former Rep. Chung Moon-hun in the contest.
The LKP has much to gain from the shifting political dynamics. The addition of nine lawmakers would bring the number of its parliamentary seats to 116, compared with the ruling Democratic Party's 121.
The LKP has been pushing to merge with the splinter party to cement its parliamentary foothold, as the ruling party is struggling to win opposition support for its legislative goals, such as retooling the tax code.
The LKP also seeks to have conservatives coalesce behind it ahead of next year's gubernatorial and mayoral elections, which are seen as a referendum on President Moon's first year in office.
Choo Mi-ae, the ruling party leader, decried the defections as a "regressive political regrouping."
"Such a political regrouping without any reform can't be accepted by citizens," she said during a party meeting. (Yonhap)