"We have finished our work and sent everything to the leaders", said the League's economics chief Claudio Borghi, one of his party's negotiating team.
The two parties have been locked in talks to reach a coalition government agreement and bring an end to two months of political deadlock following inconclusive elections.
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.
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.
For his part, Salvini said being PM would be an "honour" but added "if necessary I will step to the side".
Chances for a League-5-Star government got a boost last week after Berlusconi said he wouldn't get in the way of it, but wouldn't vote for it either. "Better to be a barbarian than a slave that sells Italy's dignity, future, businesses and even its borders".
The European Union is meddling in Italy's domestic politics, according to League leader Matteo Salvini.
A draft policy document dated Monday was leaked to the Huffington Post yesterday.
Both Mr Salvini and Mr Di Maio have warned the EU's budgetary austerity is "suffocating" Italy and have spoken out against the bloc's sanctions issued against Russian Federation following the annexation of Crimea and branded unfair for the country the EU's migration rules.
"We heard some unelected commissioner say that Italy has to continue to do what it's always done, or rather - pull its pants down", he said. He said that cuts to the five billion euro budget for asylum infrastructure would be used to pay for expulsions of "thousands of criminals".
"I see in a certain establishment such a fear of change", he said.