Italy's referendum: facts

A man walks past posters calling to vote "Yes" at the constitutional referendum in Rome on December 1, 2016

Key facts behind Italy's referendum on constitutional changes this Sunday:

- What is proposed? -

To strip the second chamber of parliament, the Senate, of most of its powers to block and amend legislation

To replace 315 elected Senators with 100 appointees from the regions

To transfer some powers currently held by local and regional authorities to central government

- Why? -

The government says the reform will end gridlock in parliament and make it easier to pass difficult legislation

Designed to complement reform of the electoral system ensuring biggest vote-winner in elections of a parliamentary majority

Savings of up to 490 million euros a year in operating costs, according to disputed government figures

- For or against? -

FOR: Prime Minister Matteo Renzi, most of his centre-left Democratic Party and his junior coalition partners. Most business leaders.

AGAINST: Main opposition parties - populist Five Star Movement, Silvio Berlusconi's Forza Italia and the far-right Northern League. Some prominent figures in Renzi's own camp, many constitutional experts

- Will it carry? -

Uncertain. Last polls before a two-week pre-vote ban gave the No camp a 5-8 percentage points lead but with many voters undecided

- If Yes wins? -

Renzi stays in power, his authority is enhanced and he can pursue plans for reforms of the education, legal and administrative systems

- If No wins? -

Renzi has said he will step aside. Most observers expect his party to form new government without him, possibly with Finance Minister Pier Carlo Padoan as prime minister

- Early elections? -

Possible but seen as unlikely before late 2017 at the earliest