The PCI was founded as the Communist Party of Italy on 21 January 1921 in Livorno by seceding from the Italian Socialist Party (PSI). Amadeo Bordiga and Antonio Gramsci led the split. Outlawed during the Fascist regime, the party played a major role in the Italian resistance movement. It changed its name in 1943 to PCI and became the second largest political party of Italy after World War II, attracting the support of about a third of the vote share during the 1970s. At the time, it was the largest communist party in the West, with peak support reaching 2.3 million members, in 1947, and peak share being 34.4% of the vote (12.6 million votes) in the 1976 general election.