Toh was among the founder members of the People's Action Party and the party's chairman from its formation in 1954 to 1981, save for a brief period in 1957 when leftists, who dominated the common membership in 1957, elected leftist leaders and took over the party leadership. The founding members were restored when many of the leftist leaders were arrested by Lim Yew Hock in his anti-communist crackdown, allowing for the restoration of the original "basement group" of Toh, Lee Kuan Yew and Goh Keng Swee, "et al" to the Central Executive Committee (CEC). Following this, Toh implemented a cadres system to prevent from the newcomer "ordinary members", including leftist sympathisers, from having undue influence over the membership of the CEC.