South Korean opposition leader Lee Jae-myung was convicted of violating election law and sentenced to a suspended prison term Friday by a court that ruled he made false statements while denying corruption allegations during a presidential campaign.

If it stands, the ruling could significantly shake up the country’s politics by potentially unseating Lee as a lawmaker and denying him a shot at running for president in the next election. But Lee, who faces three other trials over corruption and other criminal charges, is expected to challenge any guilty verdict and it remains unclear whether the Supreme Court will decide on any of the cases before the presidential vote in March 2027.

Lee told reporters that he plans to appeal Friday’s verdict by the Seoul Central District Court, which gave him a sentence of one year in prison, suspended for two years. Under South Korean law, Lee would lose his legislative seat and be barred from running in elections for five years if he receives either a penalty exceeding a 1 million won ($715) fine for election law violations or any prison sentence for other crimes.

“There are still two more courts left in the real world, and the courts of public opinion and history are eternal,” he said, apparently referring to plans to take the case to the Supreme Court. “This is a conclusion that’s impossible to accept.”

Lee, a firebrand liberal who narrowly lost the 2022 election to conservative President Yoon Suk Yeol, has steadfastly denied wrongdoing. Choo Kyung-ho, the floor leader of Yoon’s People Power Party, said the verdict showed that “justice was alive” and called for the judiciary to conclude the case swiftly.

The ruling drew intense media coverage and seemingly thousands of protesters. Surrounded by police lines, Lee’s supporters and critics occupied separate streets near the court, shouting opposing slogans and holding signs that said “Lee Jae-myung is innocent” and “Arrest Lee Jae-myung.” There were no immediate reports of major clashes.

Prosecutors indicted Lee in 2022 over charges that he made false claims related to two controversial development projects in the city of Seongnam, where he was mayor from 2010 to 2018, while campaigning as the presidential candidate for the Democratic Party.

One of the comments cited by prosecutors is related to suspicions that Seongnam city in 2015 changed the land-use designation to allow a housing project on a site previously preserved as green space due to lobbying by private developers.

Lee said during a parliamentary hearing in October 2021 that the city was instead “coerced” by the national government to make the change to the site in the district of Baekhyeon-dong. Prosecutors say there’s no evidence to back Lee’s claim, which has been denied by the Ministry of Land, Infrastructure and Transport.

Prosecutors also cited a TV interview Lee gave in December 2021, when he said he didn’t know a senior official at Seongnam city’s urban development arm during his time as mayor. Lee spoke a day after the official was found dead during an investigation into a property development project in the district of Daejang-dong, which reaped huge profits for a small asset management firm and its affiliates and raised suspicions about possible corrupt links between them, city officials and politicians.

Prosecutors argued that Lee was lying to the public to distance himself from the controversies and improve his chances of winning the election. They had sought a two-year prison sentence for him.

The court found Lee guilty over the comments related to the Baekhyeon-dong project, saying it was clear that the city’s decision to change the site’s land-use designation wasn’t based on demands by the land ministry. It acquitted Lee on most of the charges related to his Daejang-dong comments, citing a lack of evidence.