Polling continues tomorrow.

And not long after the polls close at 3pm it will be clear whether Italy's richest man wins a new mandate or loses everything: the power and prestige of high office, his monopoly on Italian television, and, conceivably, his freedom.

Most prime ministers contemplating electoral defeat probably think of memoirs, spending time with the family, and clawing back power in future. But Berlusconi's body language in the past few days, as he viciously berated his enemies and talked openly of the possibility of defeat, betrayed a man who, at 69, knows he has everything to lose.

If he wins he will consolidate his power and move to protect himself permanently from the law. He has vowed to break the magistrates who have been on his tail for over a decade. Italy's justice system is desperately overloaded, underfunded and bureaucratic. But it has a prosecuting system that enjoys remarkable freedom from political control. A top priority for Berlusconi if he gets back will be to castrate those turbulent prosecutors.

In the past five years Berlusconi has devoted most of his political energy to getting laws passed to protect himself: to allow trials to be transferred to more indulgent judiciaries, to give himself immunity from prosecution, to protect his media empire from assault on the grounds of monopoly, to forestall "conflict of interest" attacks on his position as media tycoon and prime minister. He has passed these "ad personam" laws without any sense that he was making indecent use of parliament: for Silvio Berlusconi, l'etat, c'est moi.

As his violent rhetoric of recent days makes clear, he is no longer capable of seeing a difference between his own interests and those of the nation. Anyone (like Milan's prosecutors) who is against him is a subversive. He still makes foreigners laugh, but these are some of the reasons why these days he makes many Italians gag with fright.

If he loses, his choices will be limited. He has made it clear he has no intention of going into exile or dropping out of politics.

If Forza Italia is again the dominant party on the centre-right, as is almost certain, he will insist on leading the opposition, and will not give the new government a moment's rest.

If the centre-left wins unconvincingly, he will be counting the days until its internal contradictions . . . it is a wildly heterogeneous coalition . . . cause it to unravel. Through his media assets he will harangue the government and attempt to whip up mass protests against any assault on his media power.

He is a master of this: when in 1984, during his early years as a media mogul, judges tried to close down his nationwide TV network, which was operating in a legal vacuum, he short-circuited them. Yanking popular programmes such as Dallas and General Hospital from the screens, he gave the impression that this was the work of the judges, sparking public anger. Years later he galvanised viewers into mass protests against a government plan to ban 'tele-promotions', the advertising of products on quiz or talk shows, which earned him millions a year.

When Berlusconi decided to enter politics in 1993, criminal cases against him were piling up . His empire was facing bankruptcy. A mere two months after telling viewers of his three TV stations, in a long, pseudo-presidential address, of his plan to "scendere in campo" . . . go down on to the pitch of politics . . . he was prime minister. Just seven months later, his coalition collapsed.

In the following six years of centre-left rule, Berlusconi could have faced bankruptcy and disgrace. Luckily for him, his adversaries on the left believed he was finished. They treated him as a partner, and passed a law that bettered his chance of seeing the cases against him killed off by the statute of limitations. So it was with his empire intact that Berlusconi rampaged back to power in 2001.

Massimo D'Alema, the former prime minister blamed for failing to hamstring Berlusconi in the 1990s, has vowed not to make the same mistake again. He has promised a law requiring a prime minister to put his commercial interests into a blind trust, as is done in the US. It's not in their manifesto, but the centre-left is also determined to abolish Berlusconi's latest legal reform, which halves the time allowed for white-collar criminal cases to negotiate the court system before they are annulled by the statute of limitations.

If a centre-left government keeps its act together long enough to pass these measures, he will lose all say in the content of Mediaset's TV channels and newspapers. Not only that: the two cases before the courts, including the one in which Berlusconi is accused of corruption, would stand a chance of going all the way to the highest court of appeal.

And then the man who today is still Italy's prime minister could actually find himself behind bars.