"It is not official yet, but Matteo Renzi plans to go to see the president around 4pm (1500 GMT) to formally accept the mandate as prime minister and present his ministers," a source from the PM-designate's centre-left Democratic Party (PD) told AFP.
The Florence mayor has been negotiating hard with his future coalition partners to secure a fresh cabinet line-up.
But agreement had stalled in particular over the role to be given to Angelino Alfano, head of the New Centre Right (NCD) party and former right-hand man of ex-premier Silvio Berlusconi.
Renzi must present his cabinet to Italy's president Giorgio Napolitano before the government can be sworn in and voted into office by parliament.
He had been reluctant to keep the team that worked with his predecessor Enrico Letta, who was ousted by the PD for failing to implement promised reforms.
"It cannot be a Letta government mark two", the Corriere della Sera daily quoted Renzi as saying, adding that the head of the Democratic Party (PD) "is looking to the future, and is worried."
Alfano held the post of both deputy prime minister and interior minister under Letta.
Analysts say he is unwilling to renounce a post in the new cabinet because of fears his small party -- a break-away from Berlusconi's Forza Italia party -- could fall by the political wayside.
"Renzi doesn't want (Alfano) in, to show the newness of his government compared to Letta's," but the NDC is unwilling to step back "as Berlusconi is waiting in ambush," La Repubblica daily said.
Progress has also been stalled by disagreements over who should take the economy ministry portfolio, a vital post in the eurozone's third largest economy, which is struggling with near-record unemployment and widespread disillusion following a deep recession.
Italy's main business lobby on Thursday urged Renzi to form a government "really capable" of tackling the ills of a country lumbered with a public debt equivalent to 130 percent of total economic output, where hundreds of thousands of enterprises have been forced to fold.
La Stampa daily described the protracted negotiations as an "arm-wrestle between Renzi and Alfano" and said the "obstacles risk stopping the creation of the government, or weakening it, rather than building a new coalition deal."
"An executive born under duress, rather than conviction, is surely not destined a tranquil life," Stampa columnist Marcello Sorgi warned.
However, while "the coalition is in fibrillation... Matteo Renzi is sure that it is only the tensions of the last mile," La Repubblica said.
Any delays will doubtless spark vocal reactions from critics who accuse him of putting the country's recovery at risk by grabbing power from Letta.
The former Boy Scout has already lost the confidence of many Italian voters, with 65 percent describing his abrupt ouster of Letta as a "blow to