Rep. Kim Sang-wook of the ruling People Power Party attends a plenary session at the National Assembly in Seoul, Thursday. Yonhap

The ruling People Power Party (PPP) is grappling with internal division as members are split over how to deal with the opposition-led attempt to launch a parliamentary probe into President Yoon Suk Yeol's brief declaration of martial law on Dec. 3.

The National Assembly on Wednesday rejected two special counsel bills, which called for the designation of special prosecutors to investigate Yoon's treason charges and multiple allegations against first lady Kim Keon Hee. As a result, the bills were scrapped.

In a revote at the plenary session, 198 of the attending 300 lawmakers voted in favor of the bill targeting Yoon, while 196 of them voted in favor of the bill against Kim. For a bill to pass the National Assembly in a revote, it requires a majority of the 300 lawmakers to be present and two-thirds of them to cast their ballots in favor.

Both bills were passed by the opposition-controlled Assembly last month before acting President Choi Sang-mok vetoed them, saying bipartisan compromise is a prerequisite for his approval and claiming these bills contained unconstitutional elements.

The PPP has 108 seats in the Assembly, meaning six and four of its lawmakers broke away from the party line to vote in favor of the special counsel bills on Yoon and Kim.

Rep. Kweon Seong-dong, floor leader of the ruling People Power Party, attends a plenary session at the National Assembly in Seoul, Thursday. Yonhap

After Wednesday's plenary session, PPP floor leader Rep. Kweon Seong-dong suggested that Rep. Kim Sang-wook, who voted to impeach Yoon last month and in favor of the special counsel bills, should leave the party.

"I told Kim to seriously consider leaving the party if he is unable to comply with the party line," Kweon told reporters.

Rep. Kim Sang-hoon, the PPP's policy chief, also criticized him for not aligning with the party.

"Kim (Sang-wook) has continuously deviated from the party line. So wouldn't it be better to withdraw from the party and engage in independent political activities as he wishes?" Kim Sang-hoon said in a radio interview.

However, Rep. Kim Sang-wook said he has no intention of leaving the party.

"A lawmaker can vote per one's conscience. I know only a few people believe in what I believe, but I will stay in the party and make sure our party is on the right track," he said.

Despite his wishes, Kim was removed from the Assembly's Public Administration and Security Committee.

PPP Rep. Cho Kyung-tae, who also voted to impeach Yoon last month, defended Kim, saying, "It is President Yoon who damaged the values of conservatism the most, so he's the one who should be expelled from the party."

The PPP also lacks consensus on rallying against attempts by investigators to detain Yoon. Some party members criticized the 44 PPP representatives who visited the presidential residence on Monday to protect Yoon.

"It's inappropriate to gather near the presidential residence to rally against investigators. Lawmakers trying to interfere in the investigation goes against the principles of the Constitution. Uniting conservatives is not the solution to overcome the current situation," PPP Rep. Han Zeea said in a radio interview.

Meanwhile, the main opposition Democratic Party of Korea proposed a new bill on Thursday to appoint a special counsel to investigate the treason charges against Yoon. This time, the bill includes a provision for the recommendation of the special prosecutor by a third party, such as the Supreme Court chief justice, to investigate Yoon. It plans to put it to a vote in a plenary session on either Tuesday or Thursday.