Italian Prime Minister Silvio Berlusconi said rebel lawmakers could pitch Italy into the middle of the euro zone's debt crisis if they voted against him in a no-confidence vote tomorrow.

Speaking in the Senate a day before a showdown that could force him from office and trigger early elections, Berlusconi said his government had kept Italy out of the turmoil seen in Ireland or Greece but that the threat of instability remained.

"It is madness to initiate a crisis without any foreseeable solutions," he said.

A year of party infighting and corruption and sex scandals has hit Berlusconi's leadership credentials while a scandal over waste management in Naples has made piles of uncollected garbage an embarrassingly visible symbol of the government's weakness.

On Tuesday, dubbed "B-Day" by Italian media, Berlusconi faces a no confidence motion in the lower house called by opposition and rebel center-right deputies and a confidence vote the government has tabled in the Senate where it has a majority.

The 74 year-old media tycoon no longer enjoys a lower house majority following a bitter split in July with former ally Gianfranco Fini and a group of rebel center-right deputies who have broken away from the ruling PDL party.

But after an intense campaign of lobbying and promises described by adversaries variously as a "cattle market" or "football transfer season," the government appears to have made up ground with wavering deputies.

Some commentators estimate a result as close as 314 votes for Berlusconi against 313 for the opposition is possible.

Whether that will be enough for longer term stability is unclear. Umberto Bossi, the bluntly spoken head of Berlusconi's Northern League coalition partners, expressed the skepticism of many when he said: "You can't govern with a one vote majority."