PCdoB shares the disputed title of "oldest political party in Brazil" with the Brazilian Communist Party (PCB). The predecessor of both parties was the Brazilian Section of the Communist International, founded on 25 March 1922. The current PCdoB was launched on 18 February 1962, in the aftermath of the Sino-Soviet split. Outlawed after the 1964 coup d'état, PCdoB supported the armed struggle against the regime before its legalization in 1988. Its most famous action in the period was the Araguaia guerrilla (1966–1974). Since 1989, PCdoB has been allied to the Workers' Party (PT) at the federal level, and, as such, it participated in the Luiz Inácio Lula da Silva administration and joined the "With the strength of the people" coalition, which elected his successor, Dilma Rousseff. In 2018, the party again allied with PT and the candidacy of Fernando Haddad. Haddad's running mate was PCdoB member Manuela d'Ávila.