 The moderate Poalei Zion formed Ahdut HaAvoda with Ben-Gurion as leader in March 1919.In 1920 he assisted in the formation of the Histadrut, the Zionist Labor Federation in Palestine, and served as its General Secretary from 1921 until 1935.At Ahdut HaAvoda's 3rd Congress, held in 1924 at Ein Harod, Shlomo Kaplansky, a veteran leader from Poalei Zion, proposed that the party should support the British Mandatory authorities' plans for setting up an elected legislative council in Palestine.