A referendum on the terms of integration into the Federation of Malaysia was held in Singapore on 1 September 1962. Option A, which provided for the highest level of autonomy, was the option selected on nearly 96% of valid ballots. However, 26% of voters cast blank or invalid ballots (mostly the former), meaning that Option A was only selected by 71% of those who participated in the referendum, or by 64% of registered voters. Background The first internal challenge to merger with the Federation of Malaya came from and grew out of a political struggle between the People's Action Party (PAP) and their opponents included the Barisan Sosialis (Socialist Front), the Liberal-Socialist Party, the Workers' Party, the United People's Party and the Partai Rakyat (People's Party). In Singapore, the PAP sought formation of Malaysia on the basis of the strong mandate it obtained during the general elections of 1959 when PAP won 43 of the 51 seats. However, this mandate became questionable when dissension within the party led to a split. In July 1961, following a debate on a vote of confidence in the government, 13 PAP Assemblymen were expelled from the PAP for abstaining from voting. Subsequently, they formed a new political party, the Barisan Sosialis or the Barisan, reducing the PAP's majority in the Legislative Assembly to 26 of the 51 seats. The ruling PAP was not legally obliged to call for a referendum, but did so to secure the mandate of the people. However, the Barisan Sosialis, a left-wing socialist party consisting of former PAP members with communist sympathies pedigree to the opposition to the colonialism, and imperialism movements were alleged that the people did not support merger, but Lee Kuan Yew declared that people did. The referendum did not have an option of objecting to the idea of merger because no one had legitimately raised the issue in the Legislative Assembly before then. However, the methods had been debatable. The referendum was therefore called to resolve the issue as an effort to decide objectively which option the people backed. The legitimacy of the referendum was often challenged by Singaporean left-wingers, due to the lack of an option to vote against the merger. Council of Joint Action The Council of Joint Action (CJA) founded by 19 members of the Assembly to block the merger and scuttle the referendum by taking the issue before the UN Committee on