|This article does not cite any references or sources. (January 2008)|
|Newspaper||Quotidiano dei lavoratori|
|Membership||max: 10,310 (1988)
min: 2,500 (1979)
DP was founded in 1975 as a joint electoral front of the Proletarian Unity Party (PdUP), Workers Vanguard (AO) and the Workers Movement for Socialism (MLS). At the local level, smaller groups joined, such as the Marxist-Leninist Communist Organization, Revolutionary Communist Groups - IV International and the League of the Communists.
DP took part in the 1976 elections, winning 556,022 votes (1.51%) and 6 seats in the election to the Chamber of Deputies. On April 13, 1978, DP was transformed into a political party. The move to make DP into a real political party was pushed through by the minority wing of PdUP, led by journalist Vittorio Foa and Silvano Miniati; the majority of AO, led by Massimo Gorla and Luigi Vinci; and the League of the Communists, led by Romano Luporini.
The strongholds of DP were the industrial cities of Northern Italy, which had strong leftist traditions. DP was opposed to the so-called 'historic compromise' between the Italian Communist Party and the Christian Democrats.
In the 1979 elections for the European Parliament, DP won 1 seat.
In the Italian general election, 1983 DP won 542,039 votes (1.47%) and 7 seats in the election to the Chamber of Deputies. In the Italian general election, 1987 DP won 642,161 votes (1.66%) and 8 seats in the election to the Chamber of Deputies. In the same year DP won 493,667 votes (1.52%) and one seat in the election to the Senate.
In 1987 Capanna stepped down, and Giovanni Russo Spena became the secretary of DP. Two years later, the DP suffered a split, as a section led by Capanna launched their own list on ahead of the elections to the European Parliament, called Rainbow Greens.