In the period leading up to the Sarekat Islam's sixth congress in 1921, members became aware of Sneevliet's strategy and moved to stop it. Agus Salim, the organisation's secretary, introduced a motion banning SI members from dual membership in other parties. The motion passed despite opposition from Tan Malaka and Semaun, forcing the communists to change tactics. The Dutch colonial authorities introduced more restrictions on political activity and Sarekat Islam decided to focus on religious matters, leaving the communists as the only active nationalist organisation.