Former South Korean labor minister Kim Moon-soo registered as the People Power Party's presidential candidate on Sunday, after the ruling party failed to replace him with former prime minister Han Duck-soo.

After completing the registration, Kim said the June 3 presidential election is important as it will choose a president "who must overcome the crisis South Korea is facing and who can make efforts to achieve the people's happiness".

Sunday marked the deadline for candidates to register with the National Election Commission. The campaign period begins on Monday and will last for three weeks.

Kim expressed confidence in his chances, saying he will devote the utmost efforts to make South Korea a greater country, Yonhap News Agency reported.

His registration followed a weeklong internal dispute within the People Power Party. Although Kim had won the party primary earlier this month, PPP leadership sought to unify the candidacy with independent contender Han, who had polled higher in opinion surveys.

Despite Kim's objections, the party initiated an unprecedented process to replace its presidential candidate on Saturday. Han joined the PPP in the wee hours of the day, and the head of the PPP election committee announced that Kim's nomination had been canceled.

However, the bid to replace Kim was eventually rejected in an all-party vote on Saturday evening, leading to the reinstatement of his candidacy.

Following the vote, Han said he humbly accepted the result and would support Kim's campaign.

Former president Yoon Suk-yeol said on Sunday that the PPP's presidential nomination race was marked by intense debates and difficulties, but has shown that the party's system remains normal.

Yoon said he has been grateful to the PPP, despite being caught in the turbulent whirlpool of politics following his impeachment. He was set to attend the third hearing of his criminal case over insurrection charges on Monday.

"Now is the time for unity," Yoon said, noting the upcoming election is not merely about a change in administration but about the core of South Korea's system. He also said the PPP faces a strong opposition side.

Meanwhile, Lee Jae-myung, the presidential candidate of the main opposition Democratic Party and a consistent front-runner in opinion polls, registered his candidacy on Saturday.

In a Gallup Korea poll conducted last week, Lee led a three-way race with 52.1 percent of support, ahead of Kim, who received 31.1 percent, and Reform Party candidate Lee Jun-seok, who polled at 6.3 percent, according to South Korean broadcaster KBS World.

Lee Jae-myung's support appears to have strengthened following a political merger on Friday between the Democratic Party and four progressive parties, with the withdrawal of Progressive Party candidate Kim Jae-yeon from the contest.

Legal woes

The former Democratic Party leader is facing several criminal trials related to election law violations and bribery. While some hearings have been postponed until after the election, observers said a conviction could add uncertainty to his term even if he is elected president.

The national council of judges announced on Friday that an extraordinary session will be held on May 26 to allow judges nationwide to discuss the Supreme Court's decision to send Lee's election law violation case back to the appellate court, which had previously acquitted him.

Key focus will be on restoring public trust in the judiciary and preserving judicial independence.

Yoon Yeo-joon, co-chair of the Democratic Party's election committee, said at a meeting on Sunday that the political neutrality of all state agencies is important during the election.

"At a sensitive time, the sense of balance and political neutrality of the judiciary, the administration, the National Election Commission, and the investigation agencies are very important."

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