台灣團結聯盟
After leaving office, he remained active in Taiwanese politics. Lee was considered the "spiritual leader" of the pro-independence Taiwan Solidarity Union (TSU), and recruited for the party in the past. After Lee campaigned for TSU candidates in the 2001 Taiwanese legislative election, he was expelled by KMT. Other activities that Lee engaged in included maintaining relations with former Taiwanese President Chen Shui-bian and Japan.