The prime minister's failure to reach out to working class suggest large regions will snub Mr Renzi's plan for constitutional reform.
A Demos poll has revealed Mr Renzi's reforms will be rejected by an 11 percentage point margin in the south of the country - where most of the poorest regions are located - compared with a seven-point margin across the country.
As the nation prepares for a momentous referendum, which could spark an exit from the European Union, Mr Renzi said that he would have no interest in running the country if voters reject the proposed constitutional reform.
Luca Comodo, director at polling company Ipsos, says most voters believe that rejecting Mr Renzi's plans is a vote for change, particularly in southern regions where the economic damage inflicted by the deep recession that followed the global financial crisis hit voters particularly hard.
Mr Comodo said: "The south is where protest and rage are amplified."
If the reform goes through - it will reduce the power of the senate (the equivalent of the House of Lords in the UK) and take back legal power from 20 regional governments.