Tension is rising among presidential aspirants, particularly between those of the liberal opposition circles who will soon contend in an in-party primary ahead of the earlier-than-expected election this year.

Seoul Mayor Park Won-soon blasted Moon Jae-in, former chairman and presidential frontrunner of the main opposition Democratic Party of Korea, on Sunday during a meeting with local journalists in Jeonju, North Jeolla Province.

“Moon is one of those with vested rights who needs to be eliminated,” Park said.

The activist-turned-mayor recently announced his bid in the upcoming 19th presidential election, which is likely to be held earlier than usual due to President Park Geun-hye‘s impeachment.

“Moon has already become a part of the old politics, holding supremacy in the party. He cannot be the agent of the new political reform, but is in fact subject to clean-up,” the Seoul mayor said.

Backing his argument, Park pointed out that Moon was at the helm when the party was most divided and ended up splitting in two, with the splinter group creating the current runner-up People’s Party.

“It was his incompetence and indecisiveness which caused such consequences,” Park said.

“As party chairman, he never once succeeded in leading the party into election victory and when the candlelight rallies started, he hesitated to participate.”

Calling for a complete termination of the “old system” and the creation of a new nation, Park demanded that Moon be ousted from the leadership and the presidential race.

Despite his steady lead in most of the local polls, Moon has also come under fire recently over a report by an in-house think tank suggesting that the constitutional revision be delayed until after the imminent election.

The paper also called upon the party to refrain from an opposition coalition -- an idea which Moon‘s dissenters took as a move to remove competition for the former chairman.