Ahn Cheol-soo, who merged his presidential candidacy with Yoon Suk Yeol last year, has distanced himself from the president ahead of a March election that picks the new leader of the ruling People Power Party, after the presidential office blasted him for using the term "Yoon-Ahn solidarity" for the race.

Yoon has warned Ahn not to use the term "solidarity," with presidential aides calling it "wrong" and "inappropriate," drawing a clear line that the two share no solidarity, according to reports citing insiders. Ahn stressing solidarity with the president also undermined Yoon's leadership as the commander-in-chief of the armed forces, said Lee Jin-bok, senior presidential secretary for political affairs.

Lee said those who try to gain political advantage with expressions such as “key aides to Yoon” would be recognized as a “disruptor” and “enemy” of state affairs. Ahn previously said that the conductor of Yoon’s key members is Rep. Chang Je-won of the ruling party.

In response, Ahn said he would refrain from using the expression. He only meant to treat Yoon’s state affairs faithfully and respectfully, he said.

The three-term lawmaker and centrist People Party leader ran for the presidential election in 2021. But later he dropped out of the race to support Yoon. After the merger, the former prosecutor who spent only six months in politics won the presidential race against rival Lee Jae-myung by less than 1 percentage point.

Yoon then appointed Ahn, a former doctor and founder of antivirus software company AhnLab, to lead the presidential transition committee. Ahn was rumored to have rejected Yoon’s intial offer of the prime minister position, but recently denied being offered the job.

Critics say that while a confrontation between Ahn and Kim Gi-hyeon -- backed by Yoon's supporters within the People Power Party -- could take place at a party convention, the presidential office’s involvement is unusual.

“The presidential office can express its opinion as the first party member,” said Shin Yool, a political science professor at Myongji University.

“However, it is true that its response seems like overreaction even after prodding Na Kyung-won to quit.”

When judge-turned-politician Na decided to run for party leadership and ranked first in several surveys, Yoon dismissed her from her posts as vice chairperson of the aging society committee and climate change ambassador. She then gave up her bid, apparently to stay on Yoon's good side.

“It also seems excessive for the presidential office to criticize the expression 'Yoon-Ahn Solidarity,'” Shin said.

Rep. Chang Je-won himself has said in the past called himself Yoon’s confidant, but the presidential office never took issue with it, political commentator Park Chang-hwan said.

The latest confrontation between Ahn and the presidential office came as the polls show him in the lead for the party leadership post.

In a poll conducted by Realmeter at the request of Media Tribune on 428 supporters of the People Power Party from Jan. 31 to Feb. 1, Ahn ranked first in preference for party leadership, with 43.3 percent approval. Kim was in second place with a 36 percent approval rating.

The party convention will be held on March 8 and more than 830,000 eligible party members will vote for the next leader.