(Bloomberg) -- South Korea’s prosecution of the opposition leader on criminal charges has caused rifts in the progressive bloc, with lawmakers worried it could hurt their chances of keeping control of parliament in next year’s elections.

Democratic Party leader Lee Jae-myung appeared in court Friday to stand trial on a charge of violating the election law by making false statements during his presidential campaign in 2021. Lee did not speak to reporters but he has repeatedly denied the allegations, saying he is being targeted by the president in “political repression.” 

Lee, who has also been indicted on charges including breach of duty and bribery, is likely to have more court appearances that keep his case in the headlines for months. Although he was the party’s nominee for the presidential election, narrowly losing, some prominent members are concerned he’s becoming a liability.

Kim Jong-min, a Democratic Party lawmaker, said Lee’s repeated court appearances are weakening its ability to form a united front against President Yoon Suk Yeol. The conservative leader is pushing a business-friendly agenda to counter the power of labor — a traditional base of support for the left. 

“Due to this ‘judicial risk’ of our leader, these criticisms are not getting much attention from the general public, and are even losing their impact,” Kim said in a telephone interview.

“If we don’t reform, we won’t be able to play our role to properly check the administration’s power.” 

Lee received notice there was discontent in the party in February when parliament faced a vote on whether to authorize an arrest warrant for the leader. 

Although the Democratic Party holds 169 seats in the 299-member National Assembly, more than 30 members broke ranks to make what should have been an easy rejection surprisingly close. The party’s floor leader, Park Hong-keun, said the narrow result indicated the group’s consensus was shaky.

Read: South Korean Prosecutors Seek Arrest of Opposition Leader

While the Democratic Party and its progressive allies in 2020 scored the largest parliamentary election victory since the end of military-backed rule more than three decades ago, it support rate now is the same the president’s People Power Party. They’re both at 33%, according to a weekly tracking poll from Gallup Korea released Friday. 

Yoon’s support rate also plunged to a four-month low of 30% in the same survey. 

Yoon is at a difficult juncture in his nearly year-old presidency, stumbling in his plans to increase the hours people can work each week. Surveys also show the public doesn’t support his plan to ease a simmering dispute with Tokyo by setting up a fund to pay compensation for Koreans forced to work in Japanese mines and factories during its 1910-1945 colonial rule over the Korean Peninsula.

Read: South Korea Rethinks 69-Hour Workweek After Ire of ‘MZ’ Youth

With both parties vulnerable ahead of the April 2024 parliamentary election, unity will be essential, Shin Yul, a political science professor at Myongji University in Seoul.

“If Lee refuses to resign and this scandal gets prolonged, it will only benefit Yoon’s ruling conservative party,” he said. “The longer he remains, the more likely it is that voters in the middle will turn away from the Democratic Party, and that is not a positive sign.”

©2023 Bloomberg L.P.