Kushnir made aliyah to Palestine in 1922. He studied at the Jerusalem Law School, and was certified as a lawyer. He became one of the leaders of P o l e Zion Left, and was also involved in other Marxist groups in Mandate Palestine. In 1945 he joined the Hashomer Hatzair Workers Party, which merged with Ahdut HaAvoda to form Mapam in 1948. At the time of its foundation, in 1946, the party had around 10,000 members, two-thirds of whom hailed from the Kibbutz Artzi movement. The remainder came from the urban-based Socialist League of Palestine, which was dissolved into the par- ty. The Hashomer Hatzair movement had positioned itself politically between the mo- derate mainstream Mapai and the radical communists since the 1920s. Themovement had however been reluctant to form a political party, since its leadershad felt that en- tering into party politics could push the movement into ideological deviations. Kushnir became a member of its central committee, and was amember of the secretariat of its Haifa branch. Between 1950 and 1955 he was a member of Haifa city council, and also served as chairman of the city's branch o fthe Lawyers Union. He was on the Mapam list for the 1959 Knesset elections, but failed to win a seat. However, he entered the Knesset on 1960 as a replacement for Haim Yehuda. Although he lost his seat in the 1961 elections, he returned to the Knesset on1962.