Former Prime Minister Lee Nak-yon announces his departure from the New Reform Party at a press conference held at his New Future Party headquarters in western Seoul. (Yonhap)

Former Prime Minister Lee Nak-yon on Tuesday announced his departure from the New Reform Party and resignation from its leadership, following signs of a growing rift with his co-chair, Lee Jun-seok.

The announcement which comes merely 11 days after the ex-PM and his own political party, the New Future Party, merged with the Reform Party, which was launched by the former ruling party leader, Lee Jun-seok, last month.

“I plan to return to the New Future Party and reorganize the party to prepare for the upcoming election (scheduled for April 10),” Lee Nak-yon said in a press conference held at his party’s headquarters in western Seoul.

“I would like to apologize (to my supporters) with my head bowed. It was a poor merger decision that led to a shameful outcome,” he added.

The ex-prime minister cited the New Reform Party leadership’s decision during an intra-party meeting on Monday to designate Lee Jun-seok as the chair of its election committee, making him the party’s de facto leader. Lee Nak-yon and Kim Jong-min, the co-chairs of the New Future Party and now ex-members of the six-member New Reform Party leadership committee, had boycotted the vote about whether to make Lee Jun-seok the election committee chair. However, the other four members of the leadership committee had reportedly made up their minds to elect the ex-ruling party chair as the de facto leader ahead of the vote.

Following the vote, Lee Nak-yon denounced the decision as a move by the ex-ruling party head to "privatize the party," through a statement made by his spokesperson.

“It seems they planned to erase my presence or break the coalition from early on,” the ex-prime minister said Tuesday.

“The agreement among the members of the coalition has collapsed. The agenda to hand the sole authority to make election-related decisions to only one of the co-chairs was passed forcefully and thus the spirit of democracy was damaged.”

Lee Jun-seok expressed regret over his failed partnership with the ex-prime minister and said the New Reform Party will continue to focus on its tasks ahead of the election.

“I apologize to the Korean public with a heavy heart. I only wish the best for Lee Nak-yon and his fellow New Future Party members, who will walk with us in the same direction, but with different efforts,” he said in a separate press briefing held after Lee Nak-yon’s announcement.

The New Reform Party established by Lee Jun-seok has absorbed various new third parties launched by political defectors and has led the coalition of minor parties against the nation’s two-party system. Prior to Lee Nak-yon’s departure, the party was a merger among five different third parties.

According to a Real Meter survey conducted Feb. 15-16, voters’ support for the New Reform Party, which was included in the survey for the first time, came to 6.3 percent. Other minor parties such as the Green Justice Party, launched in 2012 and one of the largest third parties here, had 2.2 percent support, while the Progressive Party, established in 2017, had 1.6 percent support.

Meanwhile, support for the ruling People Power Party came to 39.1 percent, while the main opposition Democratic Party of Korea had 40.2 percent support.

The survey involved 1,009 eligible voters across Korea aged 18 or older.