The far-right Brothers of Italy party, buoyed by a strong showing in weekend local elections, has called on Prime Minister Mario Draghi's coalition to resign after its main supporters fared badly in the vote.
Brothers of Italy, led by Giorgia Meloni, was the only major party to refuse to join the broad, unity government last year, even as its allies in the centre-right bloc, the League and Forza Italia, took cabinet seats.
The decision has enabled it to establish a clear, uncompromising identity, which has paid dividends with voters.
The party took just 4.4% of the vote in the last national elections in 2018, but polls show it now on around 22% and in Sunday's ballot for mayor in almost 1,000 towns and cities, the group emerged as clear leader of the centre-right.
By contrast, the League and the populist 5-Star Movement, which are Draghi's two largest backers in parliament, suffered major setbacks on Sunday, underscoring the difficulties they have in maintaining strong visibility in government ranks.
"We have a government which faces very important choices, deciding the fate of people, and is supported by a (parliamentary) majority that now represents very few people," said Meloni. "We can't pretend that nothing has happened."
Support for the League has fallen steadily over the past three years following a series of missteps by its leader Matteo Salvini. On Sunday, it saw Brothers of Italy overtake it in many of its traditional northern fiefdoms.
Salvini has so far shrugged off calls to quit the coalition, but he acknowledged he was struggling to govern alongside his party's historic foe, the centre-left Democratic Party (PD).
"You need a sense of responsibility to govern ... even if it is tough being in government with the PD," he said on Tuesday.
The situation is even bleaker for the 5-Star, which took 33% of the vote in 2018, but saw support crumble to under 5% in many places. The party has never shone in local votes, but Sunday's result revealed an alarming collapse across the country.
"I can say that many (5-Star voters) are really struggling with the fact that we are supporting the Draghi government," party leader Giuseppe Conte told La Stampa newspaper on Tuesday, adding that nevertheless he would not abandon the coalition.
But even if the League and 5-Star remain in the cabinet, political analyst Massimiliano Panarari said the two parties would likely make life difficult for Draghi, pushing their own agendas aggressively to gain more visibility.
"We are heading towards a period of ever greater instability," said Panarari, a professor in political communications at Rome's Unimercatorum University.
"The small saving grace is that these two leaders do not want (early) elections, because going to the polls quickly would mean certain defeat for them," he added.
The next national election is due in 2023.
(Reporting by Crispian Balmer; Editing by Alexandra Hudson)