Major changes had taken place in the structure of the Zionist Organization during the four years between the rejection of Chaim Weizmann at the Seventeenth Zionist Congress of 1931 and his reelection in 1935. The most important of these was the secession of the Revisionists, who established the New Zionist Organization in September 1935. The second was the strengthening of the Labour groups to become the central force in the movement, with 45 per cent of the delegates at the Nineteenth Congress compared with 29 per cent in 1931. Finally, there was the continued decline of the two wings of the General Zionists. These factors both necessitated and facilitated Weizmann's return to the leadership.
