Italian Prime Minister Giuseppe Conte threatened on Monday to resign, telling his two coalition partners to either end their constant feuding or seek new elections.
Mr Conte, an academic with no political support base, called a news conference to make the extraordinary ultimatum after months of bickering inside his year-old coalition of right-wing populists and anti-establishment lawmakers.
"I'm not here just to scrape by or drift," Mr Conte told reporters at his residence. "If they do not clearly assume their responsibilities...then I will resign."
The League and 5-Star Movement have been battling over everything from major infrastructure projects and immigration to the historical significance of national holidays and who was to blame for a cruise ship accident in Venice at the weekend.
The feud has intensified since European parliamentary elections last month in which the League won 34 percent of the vote, leap-frogging above 5-Star and fuelling speculation that League leader Matteo Salvini could ditch his coalition partners.
Mr Salvini took to Twitter even as Mr Conte was talking, saying he wanted to carry on. "We are ready, we want to move forward and don't have any time to lose. The League is in," he tweeted.
There was no immediate response from 5-Star leader Luigi Di Maio, whose position has been weakened by the EU election rout, which saw 5-Star lose half its support in just over 12 months.
Mr Conte said he had underestimated the impact of non-stop electioneering this year ahead of the EU vote and that a week after the ballot the atmosphere remained bad.
Mr Conte told reporters his cabinet faced a complex 2020 budget and said Italy needed the confidence of financial markets.
During the recent government infighting, investors sold off Italian bonds, raising fears for Rome's ability to manage its enormous public debt of around 2.3 trillion euros (Dh9.5 trillion).
"We must not let sterile controversies and pointless arguments waste our precious energy or distract from government objectives," Mr Conte said.
Italy faces the possibility of European Union disciplinary procedures this week for a breach of EU fiscal rules, which Salvini says are outdated and harmful to the Italian economy.
Mr Conte said any EU sanctions would be very harmful, adding that the government had to abide by EU budget rules until such time as they could be changed. Repeated sniping from within coalition ranks only undermined his position, he said.
"All problems, even the thorniest, can be tackled, but a climate of co-operation and mutual help is needed. Without this, it is difficult to face such delicate challenges."
Since the EU election, Mr Salvini has demanded extreme tax cuts for Italy and dismissed EU calls for fiscal discipline.
Italian media reported on Monday that if Mr Conte could not restore order to his government, President Sergio Mattarella would probably dissolve parliament in July and set a new election for September.