(By Emily Backus and Christopher Livesay) Rome, August 23 - Pivotal voices within Italy's centre left laid groundwork Friday for life after a possible fall of Italy's teetering left-right coalition government as the Democratic Party (PD) made it clear that banning centre-right leader Silvio Berlusconi from the Senate in a vote next month was non-negotiable. An Italian MP and candidate for leadership of the PD told the newspaper La Repubblica in an interview published Friday that the party, which holds a majority in the Senate, will throw Berlusconi from office in a September 9 vote even if it means the end of the fragile coalition led by Premier Enrico Letta, also of the PD. "We are not in the government at any cost. In this match we are playing with our souls," said Gianni Cuperlo. Removing Berlusconi from public office "is a necessary act, a given. The right must understand that we cannot retreat by even a millimetre, because our concept of democracy is at stake". Meanwhile, the historic center-left politician and ex-premier Massimo D'Alema said that the current government was fleeting from its conception, and said the PD's future looks far brighter than that of the centre right if the latter continues to stake its future on Berlusconi's judicial treatment. Speaking from PD festivities in the central Italian town of Narni on Thursday, D'Alema said, "Letta is only a transitional leader for a temporary government with a limited programme. He will not be useful a second time. In the future I imagine Gianni Cuperlo as the party secretary and (Florence Mayor) Matteo Renzi as premier". Renzi is a rising star on the conservative spectrum of the PD, and is considered by many to be an independent voice within the centre left. D'Alema denied that the current schism in the shaky left-right government poses any problem from the PD's perspective. "In the end, there will not be any crisis. If the centre-right thinks of tying its own future to Berlusconi's judicial destiny, it will have to resign itself to decline without return," said D'Alema. Letta met President Giorgio Napolitano Thursday in a last-ditch bid to avert government crisis, as the PD shunned appeals from Berlusconi's party to refrain from voting the media mogul out of the Senate on September 9 as a consequence of his August 1 conviction for tax fraud, his first definitive sentence in almost 20 years of battles with a judiciary he claims is left-wing. Berlusconi is insisting he must be allowed to continue as PdL leader and can only do that as a Senator. Otherwise, the PdL will pull the plug on the four-month-old administration Napolitano forced into existence after a two-month post-election impasse earlier this year. In February's parliamentary elections, the centre left barely beat the centre right with nearly equal shares of the vote - roughly 30% each - while comedian Beppe Grillo's anti-establishment 5-Star Movement (M5S) won a quarter of the vote. The PD tried repeatedly to team up with the M5S, but Grillo refused, forcing historic political enemies to join forces to create a majority coalition. D'Alema on Thursday said the right stood more to lose than the left should the government fall. "If (the right) want to go to elections, we're ready. But I don't believe (they do). Berlusconi knows that we are 15 points ahead of him with Renzi as leader," D'Alema said, adding that Berlusconi could continue his political career as a charismatic outsider, without any public office or official position. The remark was a nod to Grillo, who cannot serve in office due to a vehicular-manslaughter conviction, yet wields significant control over elected lawmakers in his party.