When Italian Catholicism gave up actively opposing fascism, he approached Marxist culture, also drawing inspiration from Antonio Gramsci, and gradually deviated from its own Catholic formation.

[1] In those years, Lombardi met his partner and future wife, Ena Viatto (1906–1986), who fell in love with him and separated from Girolamo Li Causi.

[1] A leader of the Italian resistance movement against Benito Mussolini during World War II, Lombardi was one of the founders of the Action Party (PdA) in 1942.

He participated in the first De Gasperi government (10 December 1945 – 1 July 1946) as Italian Minister of Transport, starting the rapid reconstruction of the railway network.

[1] On 18 June 1970, Lombardi made claims before the country's Chamber of Deputies, based on a document printed on NATO stationery, that the organization was planning to move troops into Italy as a result of the perceived political instability.