Italian Prime Minister Matteo Renzi could be the next casualty of the populist movement sweeping across the Western world, as his political opponents take succour from the election of Donald Trump as president.

Italians go to the polls on December 4 to vote in a referendum on a constitutional reform package. But the ballot is turning into a proxy vote on Renzi’s popularity, with the electorate threatening to undermine his mandate by opposing the proposals.

Renzi has spent the last few weeks rowing back from a promise to resign if he loses the referendum, The Telegraph has reported.

Both the Five Star Movement, led by former comedian Beppe Grillo, and Lega Nord (the Northern League) have predicted that Mr. Renzi’s leadership could fatally be undermined by the vote, as the country’s economy continues to stagnate while youth unemployment stays resolutely at around 40 per cent.

Following Trump’s victory, Grillo compared the win to an anti-establishment “V-Day” protest he organised in Italy in 2007. The “V” stood for “vaffanculo”, Italian for “fuck off”.

“It’s crazy. This is the explosion of an era. It’s the apocalypse of the media, TV, the big newspapers, the intellectuals, the journalists,” Grillo wrote on his blog.

“This is a wide-ranging fuck off. Trump has pulled off an incredible V-Day.”

“Journalists and intellectuals” were “anchored in a world that no longer exists,” he said, adding: “We’ve seen the same thing with our Movement.

“There are similarities between this American story and the Movement.”

The Italian press had underestimated the Five Star Movement, just as the American press had underestimated Mr. Trump, he said. “We were born and no one noticed, because we have an outdated press that only understands events after they’ve already happened, and it’s already too late.”

Meanwhile, Matteo Salvini, the leader of the Northern League, has criticised Renzi for supporting Hillary Clinton during the electoral race, thus weakening Italy’s standing with the new administration.

“His trip to see Obama [in Washington] and his good wishes towards Clinton have ended up today as a farce,” Salvini said.

Salvini met with Trump during a trip to the U.S. in April. The two men were said to be in “total agreement” on the question of the migration crisis, while Salvini has expressed admiration for Trump’s economic policies.

In turn, Trump declared: “Matteo, I hope you become Prime Minister soon.”

Congratulating Trump on his victory, Salvini said his party shared many of Mr. Trump’s policies including tax cuts, imposing a trade barrier on imports from China, withdrawing from NATO and the UN, and immigration reform. “These are all things that we have been proposing,” Mr. Salvini said.