Former Italian prime minister Silvio Berlusconi has stepped up his campaign for a No vote in a critical constitutional reform referendum on Sunday.

Italians are being asked by prime minister Matteo Renzi and his government to approve wide-ranging legislative changes, including a reduction of the powers of the senate, intended to streamline government and guarantee executive stability.

The Yes campaign has a broad range of domestic and foreign supporters that includes business leaders, the principal Italian daily newspapers, US president Barack Obama, Germany’s chancellor Angela Merkel and the international financial establishment.

Speaking to La Repubblica TV on Wednesday, Mr Renzi adopted a conciliatory tone which, in itself, acknowledged the sometimes surprising level of vitriol generated by a campaign that has dominated the autumn.

“Whether the Yes or No wins, as far as I am concerned, it will be a triumph for democracy, a triumph for Italy. I hope that it will be a great festa and that lots of people vote,” he said.

With many commentators speculating the Mr Renzi might resign if a reform programme in which he has invested much political capital is rejected by the electorate, the prime minister appeared to reject this analysis.

“I make a solemn commitment not to consider the result of this referendum in [party] political terms but rather . . . as votes for the Yes and the No,” he said. “However, from December 5th on, things change . . . It is self-evident that, whatever the result it, it will have an impact on the government.”

Unlikely bedfellows

Mr Berlusconi, who surprised many by bouncing back into active political life last weekend to call for a No vote, told RAI TV that, if the referendum was passed, a subsequent election victory for Mr Renzi would leave him in charge of both the lower and upper chambers of parliament as well as the constitutional court.

When his interviewer attempted to interrupt him, Mr Berlusconi threatened to leave the television studio, saying: “No, no, this interview cannot go on like this. Either you give me time to answer your questions on serious issues or I am going to walk out. I’m trying to tell Italians just why it is anti-democratic to vote Yes.”

Dramatic entrance

“I have never really liked politics but at this particular moment, just as in 1994, I feel a sense of responsibility to my country and to Italians. What is being presented now to Italians as a reform, in my opinion goes contrary to democracy,” he said.

One of the main arguments proposed by the No side is that, combined with new electoral reform legislation already approved by parliament, the referendum package would put too much power in the hands of the prime minister.

That point was underlined by Virginia Raggi, Rome’s 38-year-old, M5S Mayor.

She told the CBS 60 Minutes programme: “This is crazy, this is madness. Democracy means having the right to choose your own representative. He [Mr Renzi] doesn’t want to change the country, he just wants more power . . . to do what he wants, maybe to enact all sorts of legislation without any parliamentary opposition.”

The final opinion polls gave the No side a narrow lead, making this vote too close to call.