In 1966, when the PDPA Central Committee was expanded, Amin was elected as a non-voting member, and in the spring of 1967 he gained full membership. Amin's standing in the Khalq faction of the PDPA increased when he was the only Khalqist elected to parliament in the 1969 parliamentary election. When the PDPA split along factional lines in 1967, between Khalqists led by Nur and Parchamites led by Babrak Karmal, Amin joined the Khalqists. As a member of parliament, Amin tried to win over support from the Pashtun people in the armed forces. According to a biography about Amin, he used his position as member of parliament to fight against imperialism, feudalism, and Reactionary tendencies, and fought against the "rotten" regime, the monarchy. Amin himself said that he used his membership in parliament to pursue the class struggle against the bourgeoisie. Relations between Khalqists and Parchamites deteriorated during this period. Amin, the only Khalq member of parliament, and Babrak Karmal, the only Parcham member of parliament, did not cooperate with each other. Amin would later, during his short stint in power, mention these events with bitterness. Following the arrest of fellow PDPA members Dastagir Panjsheri and Saleh Mohammad Zeary in 1969, Amin became one of the party's leading members, and was still a pre-eminent party member by the time of their release in 1973.