Immediately after his graduation Quercini got involved in politics and served as a member of the national secretariat of the Italian Communist Youth Federation, youth wing of the PCI.[2] He was also the director of the magazine Nuova Generazione in the same period.[2] He was elected as a member of the PCI's central committee in 1969.[2] He was named as the secretary of the PCI's Catania branch in 1972.[2] He became the regional secretary of the PCI in Tuscany in 1978 and was elected as a city councilor in Catania.[2]
Quercini was elected as a city councilor in Catania in May 1985 and resigned from the post on 14 May 1987.[2] Quercini was elected to the Parliament in 1987 from the Florence constituency.[2] He was the group leader of the PCI in the Parliament.[3] He continued to serve in the same post for the PSD which replaced the PCI in 1991.[1] His term at the Parliament ended in April 1992.[1]
Quercini was among the contributors of the Communist magazine Rinascita.[4]
