Prime Minister Giuseppe Conte on Monday urged members of the anti-establishment 5-Star Movement to back a new coalition with opposition Democratic Party (PD) as the group is due to hold an online vote on the matter on Tuesday.
With the outcome of the vote uncertain, Conte said in a Facebook video the proposed coalition would be good for Italy.
"I understand your doubts, but there is a unique opportunity to show we can really decisively reform this country and do extraordinary things," said Conte, a law professor who has no political affiliation but is seen as close to 5-Star.
"To do this we don't need superheroes that my son likes so much. It's sufficient to have people who are normal but responsible and determined, who love their country more than anything else."
Conte has held a round of talks with both 5-Star and PD leaders after his previous government collapsed when the far-right League pulled out in an effort to trigger early elections.
Shortly after he spoke, 5-Star leader Luigi Di Maio also took to Facebook, but he delivered a more subdued message and refused to advise his party members on how to vote.
An opinion poll for La7 television channel said 51% of 5-Star supporters backed a tie-up with the PD, while some 69% of PD voters endorsed the idea.
PD leader Nicola Zingaretti said he was confident a deal would be reached.
"We are working as you know with patience and in a serious fashion for the formation of a real government of change, because this is what Italy needs to rekindle the economy," he told reporters.