Police sought an arrest warrant Wednesday for the suspect in the stabbing attack against opposition leader Lee Jae-myung, as Lee has remained hospitalized after surgery.

The suspect, identified only by his surname Kim, 67, stabbed Lee, the chairman of the main opposition Democratic Party (DP), in the neck while posing as an autograph-seeker Tuesday morning during Lee's visit to the southeastern city of Busan.

The attack occurred after Lee toured the construction site of a new airport on Busan's Gadeok Island.

Kim was immediately overpowered and detained at the scene.

The Busan Metropolitan Police Agency filed for an arrest warrant to formally arrest Kim on charges of attempted murder, police officials said. Earlier, the police revealed that Kim had confessed to intending to kill Lee.

Earlier in the day, the police sent officers to search Kim's residence and his realtor's office in the central city of Asan and seized his PC, laptop, a knife sharpener and other evidence as part of their investigation, focusing on determining the exact motive behind the attack.

Police also disclosed circumstantial evidence suggesting premeditation, such as the purchase and modification of a 17-centimeter mountaineering knife for the crime.

The suspect's history also indicates that he followed Lee's planned tour of southern cities, officials said. The suspect arrived in Busan on Monday, visited the adjacent city of Ulsan later that day, and returned to Busan on Tuesday.

Later on Wednesday, the agency also dispatched investigators to offices of the DP and the ruling People Power Party (PPP) to confirm whether Kim is affiliated with any political party.

Police believe that determining whether the suspect is a party member is an important factor in finding the exact motive.

Earlier, the police said Kim had plotted his attack alone, but his motive remains unknown.

Meanwhile, Lee was transferred to the general ward at Seoul National University Hospital on Wednesday afternoon from the intensive care unit (ICU), where he had been hospitalized since undergoing a two-hour surgery the previous day.

"Chairman Lee is in the ICU, and visitation is only allowed for family members," party spokesperson Park Sung-joon had earlier told reporters, adding that even party leadership members were unable to meet Lee.

Lee, who suffered an injury to his jugular vein, was airlifted by a helicopter from Busan to Seoul on Tuesday.

"Lee was stabbed in the jugular vein and underwent vascular reconstruction surgery, which included the removal of blood clots," the party's spokesperson, Rep. Kwon Chil-seung, said in a press briefing Tuesday.

President Yoon Suk Yeol and rival parties unanimously expressed deep concern over Lee's safety and condemned the attack, emphasizing that such violence should never be tolerated under any circumstances.

The attack occurred just 100 days before the country holds parliamentary elections in April, as the PPP seeks to regain its majority from the DP.

Both parties scaled down large-scale events and other schedules, with the DP urging its members to refrain from making political interpretations of the attack or comments about the suspect.

"Members, please refrain from being swayed and, aside from expressing wishes for Lee's recovery, avoid making political interpretations or mentioning the suspect in relation to the incident," Rep. Hong Ik-pyo, the floor leader of the DP, said in a text message to the party members.