Al-Rikabi supported the Nasserist faction—supporters of Gamal Abdel Nasser—in a power struggle within the Ba'ath Party in the late 1950s against the Aflaqites, supporters of Michel Aflaq. He agreed with Abdullah Rimawi's observation that the National Command, the ruling organ of the Ba'ath Party, had deviated from Ba'athist thought. Al-Rikabi tried but failed to get the Iraqi Regional Branch of the Ba'ath Party to break away from the National Command, and on 15 June 1961 he was expelled from the party. From then on al-Rikabi was a prominent Nasserite, active first in Rimawi's Revolutionary Ba'ath Command and then in Arif's Arab Socialist Union. Following the Ba'ath Party's seizure of power in the 17 July Revolution of 1968, al-Rikabi was arrested. He was killed by fellow inmates according to an official account, media unaffiliated to the Iraqi state claimed he was killed by the Iraqi security services.