The leaders of Italy's far-right League and 5-Star Movement are set to tell President Sergio Mattarella who will lead the coalition government.
Over the weekend, a majority of Italians participating in an informal ballot approved a policy agenda from the two parties.
League leader Matteo Salvini insists it has to be respected.
"We have done something which has never been done before in the history of Italy's Republic," he said. "The definition of a programme, point after point, to be respected month after month. if someone doesn't respect it, everything will break up."
The Five Star movement asked its members to vote in an online on Friday with 94% saying 'yes' in favour of the programme. The League said 91% voted 'yes' in its poll.
But will this be enough to convince President Mattarella who's very protective of Europe and Italy's NATO membership? He already seems wary of the League's pro-Russian stance and it may take him some time to make up his mind after his meeting with the two party leaders on Monday.