[1][2][3] He was elected to the Volksraad (the colonial legislature) in 1935 as a representative of the Partai Tionghoa Indonesia (PTI: the 'Chinese-Indonesian Party'), and – after Independence in 1945 – headed the Balai Harta Peninggalan [id] (the ‘Public Trustee Office’) in Central Java until retiring in 1960.
[1][2] Ko attended the Europeesche Lagere School (ELS) in Magelang and the Hogere Burgerschool (HBS) in Semarang; both institutions only admitted elite European students and a very small number of select non-Europeans.
[1][2][3] At the HBS, he founded a western-style club, named ‘Djien Gie Lee Tie Sien’ after the five Confucian virtues, which Ko – conversant only in Malay, Dutch, Javanese and European languages – studied in western translations of the Chinese classics.
[1][3] Unlike the so-called Sin Po group, which promoted loyalty to the pre-war Republic of China, CHH's political allegiance was to the Dutch East Indies as the homeland of the Indies-born Chinese-Indonesians.
[1][3] At his own initiative, Ko set up PTI's Semarang branch on 9 October that year, acting as its chairman before being elected in 1934 as president of the party's central board in succession to Liem.
[8] Ko's politics, while progressive, did not go far enough for more left-leaning members of the PTI – including Liem, Tan Ling Djie and Tjoa Sik Ien – who, espousing socialist or even communist sympathies, advocated anti-Dutch Indonesian nationalism and rejected cooperation with the Dutch colonial state.
[1][3] After the Japanese occupation of the Indies (1942–1945) during World War II, Ko joined the Partai Nasional Indonesia (PNI) of his Indonesian Leiden contemporaries in 1945, but did not further his political involvement.