The long-awaited announcement, made by party secretary Guglielmo Epifani, comes after months of speculation over who will lead the party.
The national assembly “will discuss the rules and time period of the congress (local, regional and national). The political indication is to do everything, make statutory changes and decide which to adopt, before November,” the party said in a statement published in La Repubblica.
While the PD stopped short of confirming a precise date for a leadership vote, November 24th is the most likely date, according to Italian media.
The move follows months of infighting after PD leader Pier Luigi Bersani stepped down in April following his party’s poor performance in the February elections.
The centre-left party lost a strong lead as former premier Silvio Berlusconi made a remarkable election comeback as leader of the centre-right People of Freedom (PdL) party.
Around a quarter of votes also went to Beppe Grillo’s insurgent party, the Five Star Movement (M5S), leading to a two-month political stalemate as no party won a clear majority.
Eventually, President Giorgio Napolitano picked PD politician Enrico Letta to form a coalition government.
But if the unelected prime minister wants to democratically establish himself as party leader, he faces a difficult battle against Matteo Renzi.
Renzi lost out to Bersani in the December 2012 primaries, but the 38-year-old mayor of Florence has been widely tipped for the top job.
While he faces criticism from the more traditional PD members, his slick campaign has been hugely successful with Italians.
During the political stalemate he was the most popular politician to lead a new government, polls showed. Renzi’s popularity has endured and a July poll found him to be the Italian people's favourite politician to go on holiday with, Il Sole 24 Ore reported.