The leader of the far-right Five Star Movement, Luigi Di Maio, has warned people away from voting for Democrats candidate Mr Renzi claiming it would be a “wasted vote”.
The Five Star party is resonating with frustrated Italians with its anti-establishment, anti-immigrant message.
Mr Di Maio said on an Italian TV show: “Voting for the Democratic Party is wasting your vote, Renzi is under 20 per cent.
“I think Italians do not want to see Berlusconi fighting with Salvini.”
Matteo Salvini is the leader of the Lega Nord political party, which is a rightwing populist party in Italy.
Since 2013, Berlusconi has led a revived Forza Italia, which is a centre-right political party with liberal-conservative views.
Mr Renzi has vowed not to forge a union with the far right Five Star Movement (M5S) if he were to win the vote.
He said to Italian media: “Coalitions? I prefer to win.
“I would prefer to win and see that the Democratic Party is the first party.
“However, I totally agree, no alliances can be made with extremists or the Five Stars movement.
“It’s a paradoxical election campaign, I do not remember an election campaign so divided and divisive.”
Mr Renzi served as the Prime Minister from 2014 until 2016 after the rejection of his constitutional reform.
Walter Veltroni, the former first leader of the Democratic Party said: “Berlusconi is the enemy, if there’s no majority, we will vote again”
“Berlusconi is and will remain to be the main exponent of the rival team.
“After the vote, if there is no clear majority, it is necessary to change the electoral law and return to the polls.”
“We belong to the generation that led the left wing to the government”.
The polls show that the centre-right coalition, led by Silvio Berlusconi’s Forza Italia, is in the lead.
Italians will head to the polls on Sunday March 4th and experts think a coalition is the most likely outcome.
Additional reporting by Maria Ortega.