The party was founded in 1970 as the Movimento Reorganizativo do Partido do Proletariado (MRPP), led by Arnaldo de Matos.

In 1971, the party began to publish a newspaper called "Luta Popular" (People's Struggle), directed by Saldanha Sanches.

The party was among the most active resistance movements before the Carnation Revolution, especially among students in Lisbon.

[citation needed] The party's youth wing, now extinct, was the Marxist–Leninist Students Federation, to which José Manuel Durão Barroso, a future Prime Minister from the centre-right Social Democratic Party, briefly belonged.

[citation needed] Despite this, the party contested the 2017 local elections, gaining 12,387 votes (0.24%) but losing the two council seats they held.