The leaders have been in talks on a coalition agreement in order to bring an end to over two months of political deadlock following inconclusive elections. "The next few days will be crucial", Luigi Di Maio told reporters after meeting with Mr. Mattarella.
On Wednesday morning Salvini said that negotiations were nearing conclusion, while Di Maio confirmed the two parties could wrap up the "contract of government" within the day.
His words were backed up by Guglielmo Picchi, an MP and senior policy adviser for Lega.More news: NAFTA deal unlikely this week, but negotiations continue, Mexico says
"There is no time to lose, there is no space for technocrat government", League leader Matteo Salvini said in a statement.
Salvini said the League wanted "strong government and a tax and security revolution", but admitted it remained "far apart" from M5S on several issues.
A draft policy document dated Monday was leaked to the Huffington Post yesterday. Italy, along with Greece, has taken the brunt of the Mediterranean migrant crisis and has been credited with saving Europe's honour for its efforts to save lives at sea.More news: Rouhani says Iran may remain part of nuclear accord
But the two parties may disagree on how to put their policies into action, with Five Star looking less ready than Lega to an open war.
In a Facebook video, Di Maio said that the establishment feared change but "the more they attack us the more I am motivated" to reach a deal.
"We are prepared for talks on issues like the European Union budget that will constrain this Government and the next - they say "Let's see what happens".More news: BT overhauls consumer business with bid to combine mobile and broadband
Carla Ruocco, a Five Star lawmaker, added: "We want balance and the wellbeing of the country within the European framework, we've always said this".