[2] Sullo was named as the national leader of a leftist faction (Italian: Sinistra di Base) in the party.

[5] Next Sullo was named as the minister of labor and social security on 26 July 1960 to the cabinet led by Amintore Fanfani and served in the post until 20 February 1962.

[4] Sullo was the minister of public works between 21 February 1962 and 20 June 1963 in the next cabinet led by Amintore Fanfani.

[4] From June to December 1963 he continued to serve in the same post in the subsequent cabinet headed by Giovanni Leone.

[1] In March 1974 Sullo resigned from the Christian Democracy and joined the Italian Social Democratic Party in June that year.