Giuseppe Conte spoke to parliament after it was recalled from its summer recess to decide the future today. He claimed Mr Salvini was seeking to cash in on his rising popularity. Mr Conte told a packed Senate, while Mr Salvini sat next to him: "(Salvini) has shown that he is following his own interests and those of his party.
"His decisions pose serious risks for this country."
Mr Conte, who belongs to neither of the coalition's two parties, is expected to hand in his resignation later in the day.
This will allow the head of state to start formal consultations with parties to see if a new coalition can be formed.
If this doesn't happen, President Sergio Mattarella would dissolve parliament.
Italian Prime Minister Conte has said he will resign (Image: GETTY)
While Mr Conte was speaking about him, Mr Salvini shook his head, rolled his eyes or nodded to League senators.
On the other side of Mr Conte sat Luigi Di Maio, head of the League's now-estranged coalition partner, the 5-Star