Supporters of Silvio Berlusconi threatened to resign from Italy's government on Friday after a verdict against the billionaire tycoon that could place him under house arrest and eject him from parliament.
"We are ready to resign to defend our ideal," Interior Minister Angelino Alfano, Berlusconi's closest ally from the People of Freedom party, was quoted by Italian media as saying at a meeting with the mogul.
Berlusconi himself reportedly said: "We have to ask for new elections as quickly as possible and win them."
Prime Minister Enrico Letta, who presides over the uneasy alliance between his centre-left Democratic Party (PD) and Berlusconi's centre-right coalition, earlier pleaded for calm "for the good of Italy".
But he added: "I do not think a deterioration is advantageous and I do not believe that continuing at any cost is in the interests of the country."
Italy's current government was installed following a two-month deadlock between Berlusconi and their eternal rivals, the PD, after close-run February elections in which both won around a third of the vote.
"The government is a dead man walking," the Il Fatto Quotidiano daily said in an editorial.
Opinion polls based on surveys carried out in the run-up to Thursday's verdict indicated that Berlusconi's coalition would win new elections by a large margin.
A key question will also be whether Letta will manage to contain growing discontent within the PD about governing together with a confirmed criminal.
"It is impossible to imagine that the PD can remain allied to the party of Silvio Berlusconi," said Nichi Vendola, leader of the small leftist opposition party Left, Ecology and Liberty.
Some leftists have called for the 76-year-old Berlusconi to be expelled from the Senate as soon as possible, with the Five Star protest movement calling for an immediate vote on his ousting.
But Alfonso Stile, a law professor at Rome's Sapienza university, said the procedure to exclude him from parliament would be "long and tortuous" and would be a similar to a re-run of the tax fraud trial.
Italy's top court on Thursday handed Berlusconi his first definitive conviction in a 20-year political career dogged by legal woes and sex scandals.
The court ordered the three-time premier to do a year of community service or be placed under house arrest -- a sentence due to be enacted in October.
He is also barred from running in elections for six years and the police on Friday withdrew his passport to prevent him from leaving the country.
An embittered and visibly shaken Berlusconi delivered a video message on Italian television late Thursday in which he dismissed the sentence as baseless and vowed to continue his political career.
The case against Berlusconi revolved around the purchase of film distribution rights by Mediaset -- the platform for his first entry into politics.
Berlusconi is still appealing convictions in two separate cases for having sex with an underage prostitute, abusing his prime ministerial powers and leaking a police wiretap to damage a political rival.
Other fraud and bribery charges against him over the years have either been overturned on appeal or have expired under the statute of limitations thanks to Italy's slow-moving justice system.
Berlusconi has been repeatedly written off in the past but re-emerged thanks to his formidable political skills and charisma on the campaign trail.
Some analysts on Friday predicted his long career in the spotlight was over.
"Starting today, we are beginning a post-Berlusconi Italy," said Stefano Folli, a columnist for the Il Sole 24 Ore business daily.
Marcello Sorgi, writing in La Stampa, said: "His time is over... The question now is not whether Berlusconi will leave the scene or even when but how."
Giovanni Orsina, a politics professor at LUISS university in Rome, was more wary.
"Those who think this story is over or nearing the end are mistaken," he said. "The end will be long and risks being bloody".
Italians reacted with little surprise but underlined the significance of the ruling -- Berlusconi's second and final appeal in the seven-year legal case.
"This conviction is important for everyone, not just Berlusconi," said Paolo Grazioli, a 76-year-old pensioner.
"But one thing is for sure -- he is not going away to a retirement home."