Di Maio said he had read one showing the group could manage to form a parliamentary majority – an outcome that public polls have suggested is within reach only of the centre-right.
Rightist leaders accidentally revealed fears on Thursday that a 5-Star triumph in the south could endanger their chances.
“They are doing really well, really well,” Giorgia Meloni, head of Brothers of Italy, told her allies at a joint rally in a private conversation that was picked up by an open microphone.
Raffaele Fitto, head of the tiny”We’re With Italy” party, added that support for the PD was “collapsing” in the south.
“Oh God,” said Matteo Salvini, leader of the anti-Europe, anti-immigration League, adding he hoped support for the PD remained above 20 percent to help hold off 5-Star.
At Friday’s rally, comedian Beppe Grillo, who founded 5-Star in 2009 in protest against a cronyistic political class, acknowledged the more moderate stance the movement has taken under Di Maio, but said it should remember its roots.
“Even if we go there and do amazing things, we have to remember our hearts, what drove us, the big speeches, the fighting talk,” he said.