Italians are voting in a referendum on changes to the Constitution.
The ballot, called by Prime Minister Matteo Renzi, aims to reduce the number of seats in the Senate from 315 to 100.
Renzi wants to speed up the legislation process.
He said he would resign if his ‘yes’ campaign is defeated.
Opinion polls suggest he is in trouble the ‘no’ camp is led by the popular and charismatic leader of the Five Star Movement Beppe Grillo.
Anti-establishment parties will receive a boost with a ‘no’ vote, not only the Five Star Movement, but also the far-right Northern League.
If ‘no’ wins then Grillo will feel empowered to call for a referendum on whether Italy should stay in the euro.
If that is the case then the EU faces a potential crisis within the euro area and in Italy, the zone’s third largest economy.
The recent surge in populist politics has EU leaders on the back foot as pressure to dismantle the European dream grows.