The government has a majority in the Senate, or upper house of parliament, and is expected to win the first of two votes there.
But all eyes will be on the Chamber of Deputies, where Berlusconi no longer has a guaranteed majority following a bitter rift over the summer with the co-founder of his party and one-time ally, Gianfranco Fini, a fascist-turned-moderate who is the speaker of the lower house.
If the government loses the vote in the Chamber of Deputies, Berlusconi will be forced to resign.
Italy’s president, Giorgio Napolitano, would then most likely appoint an interim leader, who would run the country until fresh elections can be held, most likely in March.
But even in this worst-case scenario, all is not lost for Berlusconi. His past as a salesman makes him a superb political campaigner and he is able to communicate directly to Italians through his control of the majority of Italy’s main television channels.
He could very well bounce back and be re-elected as leader of the new government, albeit with diminished support in parliament.
In a last-minute appeal to wavering MPs, Berlusconi said today that it would be “folly” to precipitate a political crisis at a time when Italy is facing the sort of economic pressures that have created chaos in countries like Greece and Ireland.... I ask you ... to reflect on the political folly that opening a crisis without visible and credible solutions would be today."
The key to Berlusconi's longevity lies partly in the fact that the alternative is so unpalatable to many Italians. The main opposition Democratic Party, from the center-left, has been weakened by constant changes of leadership and a lack of unity.