On Thursday evening, League leader Matteo Salvini said it would be handed to Mattarella on Monday, by which time he and Di Maio should also have their candidate for prime minister.
At a business forum on the shore of Lake Como in September previous year the leaders of Italy's soaring populist parties brushed off suggestions that they wanted to lead their country out of the euro.
Italy's two populist leaders are brushing off fears in Brussels and the markets over the outlines of their possible government, and are insisting they are close to a deal created to help ordinary Italians.
Italian newspaper il Giornale - otherwise highly supportive of Salvini's populist Lega party - declared the delay the work of amateurs, noting that new discussions could add days more onto Italy being without a functioning government.
The League and 5-Star have held a week of talks aimed at putting together a coalition government and ending more than 10 weeks of political stalemate following an inconclusive election on March 4. Italy's 10-year bond yield climbed almost 19 basis points to 2.13 percent and that was its highest level since early March and the biggest one-day rise since March 2017. Prime Minister Silvio Berlusconi was toppled in 2011 as a former European Union commissioner and economics professor Mario Monti was installed as his "technocratic" replacement after the Union decided the country had not been run to their satisfaction.
Italy, along with Greece, has borne the brunt of the migration crisis, while other European Union countries such.
The 39-page draft, obtained by Huffington Post Italia, reflected the difficulties the two pre-election rivals face in finding the resources needed to pay for promises they made to their voters during the campaign.More news: Vaping turns deadly as exploding pen launches projectile into Florida man's head
The Commission, with just a year of its term remaining, "can't really do much other than put Italy's finances under greater scrutiny, and markets don't care about that", he said.
A government led by Italy's populist 5Star Movement and far-right League would seek to renegotiate European treaties and call for a "radical reform" of the EU's stability and growth pact, according to a leaked copy of the parties' draft coalition agreement.
One of the most notable areas of interference by the European Union is over the matter of mass migration.
Moments earlier, a 5-Star source had said the programme had been substantially agreed and that it contained no reference to a possible exit from the euro or "anything that could cause any concern regarding Italy's euro membership". The two eurosceptic parties intend to water down recent labour-market reforms and have raised the prospect of a "parallel currency", an eventual replacement for the euro. However, the League still wants to leave the euro zone as soon as politically feasible. Both leaders plan to ask party members to vote on the plan before they present it to president Sergio Mattarella.
They are now using less strident tones, and a 5-Star official said on Friday any plans to raise the budget deficit will first be discussed with Brussels in a "courteous" way.
Francesco Galietti, head of the Policy Sonar political risk consultancy, described the nascent coalition's economic policies as "a pretty spicy dish", but he said investors were pleased to see that Italy was managing to form a government.