Its leader was Giuliano Pisapia, a former member of the Chamber of Deputies (1996–2006) for the Communist Refoundation Party (PRC) and later mayor of Milan (2011–2016) as an independent close to Left Ecology Freedom (SEL).

The CP, which was launched in Milan by Pisapia and sponsored by Laura Boldrini, Gad Lerner, Bruno Tabacci (leader of the Democratic Centre, CD) and others in February 2017,[2][3] aimed at unifying the portion of the Italian left interested in forming an alliance with the centre-left Democratic Party (PD).

A large splinter group from SEL, led by Arturo Scotto, Massimiliano Smeriglio and Francesco Ferrara, looked set to join forces with Pisapia,[6][7] but eventually joined the Democratic and Progressive Movement (MDP), a party founded by left-wing splinters from the PD (Roberto Speranza, Pier Luigi Bersani, Massimo D'Alema, etc.)

[11][12][13][14] In July 2017 the MDP and the CP organised a joint rally in Rome,[15] but the two parties finally parted ways in October.

[18] In December 2017 the MDP and SI launched Free and Equal (LeU),[19] while the CP was instead trying to organise a pro-PD left-wing grouping, possibly along with the Italian Socialist Party (PSI) and the Federation of the Greens.