Lange joined the Labour Party in 1963, and helped in the campaigns of Phil Amos in 1963 and Norman Douglas in 1966. In 1974 his cousin Michael Bassett suggested that Lange should stand on the Labour ticket for the Auckland City Council. The Council was dominated by conservative interests and the only Labour candidates elected were Jim Anderton and Catherine Tizard; Lange was "...halfway down the field ... which was better than I expected." Lange's father Roy, who was a doctor at Otahuhu, had delivered Bassett. The two would later have strong disagreements, prompting Lange to remark, "My father had delivered him, and it became plain in later days that he must have dropped him."