Attempts at a fragile truce between left and right in Italy's unstable coalition faltered as Berlusconi's People of Freedom (PdL) party lashed out at leftist lawmakers who are refusing to delay the talks.
"We are aghast at the Democratic Party's behaviour," vice-premier and Berlusconi protege Angelino Alfano said as a cross-party senate committee prepared to resume the hearings on Berlusconi's fate at 1800 GMT.
"For the sake of legally eliminating their historic political enemy, they are willing to bring a country to its knees," he added.
The hearings which began on Monday aim to decide whether the former premier should be ousted following his definitive criminal conviction for tax fraud in August.
Berlusconi's allies want the hearings delayed pending a ruling on the validity of a new law aimed at cleaning up politics, threatening to bring down Prime Minister Enrico Letta's ruling coalition if the left refuses to agree.
The debate has become all-consuming, sparking concerns that it could hurt the eurozone's third largest economy as it struggles to exit a recession that has led to record unemployment levels.
Bank of Italy governor Ignazio Visco warned on Tuesday that "investor concern over possible political instability" could be a drag on economic recovery, though the market reaction to the squabbling was muted.
PdL senator Francesco Nitto Palma has accused defiant centre-left committee members of "an act of war" while the PdL leader in the upper house, Renato Schifani, has likened the 23-member committee – in which the Democratic Party (PD) has the largest number of members – to a Nazi gas chamber.
The initial hearings have centred on questions on the validity of a new law which was adopted last year with the aim of cleaning up Italian politics.
Berlusconi has complained that the law, intended to rid parliament of criminals and approved with votes from his own party, in fact violates his rights.
The PdL has called for hearings to be delayed until an appeal to the European Court of Human Rights on the law can be heard, which could take several months.
Billionaire tycoon Berlusconi, who has been in parliament ever since entering politics in 1994, is determined to avoid the humiliation of ejection.
His political fate has taken political centre stage, following a supreme court ruling that turned down the 76-year-old's final appeal against the tax fraud conviction and upheld a 12-month sentence.
He cannot be shelved without a full vote in the upper house. While a hearing next month should decide whether he will be committed to house arrest or community service, the debate before the senate vote on his political status could drag on for months.