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Former Premier Silvio Berlusconi begged his fellow senators on Monday not to kick him out of Parliament, claiming new evidence proves he didn't commit the tax fraud that has threatened his political future.

In a last-ditch bid to stave off a Senate vote that could keep him out of public office for years, Berlusconi claimed that new affidavits from 12 witnesses and 15,000 pages of documentation from Hong Kong prove he is innocent.

The claim is legally moot: Berlusconi's conviction for tax fraud has been upheld by Italy's highest court, and such rulings are final. But the masterful politician is still aiming to convince the court of public opinion 48 hours before the scheduled Senate vote.

In the letter to senators from the center-left Democratic Party and populist Five Star Movement, Berlusconi set aside his typically combative tone and painted himself as a concerned elder statesman, saying he understood their indignation and "authentic love for Italy," but that freedom itself was at stake.

"I ask you to truly reflect in the intimacy of your conscience ... before taking a decision that concerns not just myself but our democracy," he said.

The 77-year-old media mogul has said his removal from Parliament would amount to a government coup, even though he has no role in the government.

Berlusconi was convicted last year over the purchase of rights to broadcast U.S. movies on his Mediaset empire through a series of offshore companies that involved the false declaration of payments to avoid taxes. His defense argued that he was busy in politics at the time and no longer involved in managing the day-to-day activities of the business.

Berlusconi read aloud the text of an affidavit by a one-time manager of a U.S. company who insisted the billionaire had nothing to do with the film deals.

Italy's high court upheld the conviction and four-year prison sentence on Aug. 1. A 2012 law bans anyone sentenced to more than two years in prison from holding or running for public office for six years.

Berlusconi's lawyers have argued the 2012 law can't be applied retroactively to crimes allegedly committed before it was passed, but the Senate vote to expel him appears poised to go ahead unless his allies can pull off a last-minute delay.

Ever since the high court ruling, Berlusconi has been battling to keep his power base intact, with decreasing success. On Oct. 2 he was humiliated in Parliament when he was forced to back down from his threat to bring down the government after his ministers refused to back him.

Then on Nov. 15, his onetime political heir, Angelino Alfano, split the center-right, refusing to join Berlusconi's new Forza Italia party and launching his own New Center-Right with dozens of lawmakers opposed to the hawkish direction Forza Italia was taking.

Berlusconi has also lost the backing of Italy's president, Giorgio Napolitano, who could have pardoned him. Napolitano had said he would consider any request for clemency over the tax fraud conviction, but Berlusconi said over the weekend in a heated attack on the head of state that Napolitano should grant the pardon without even being asked.

Late Sunday, Napolitano's office made clear it would do no such thing, and in turn chastised Berlusconi for his tone and behavior that "went beyond the limits of respect for institutions."

As a result, Berlusconi's performance on Monday appeared aimed primarily at rallying his base, who have been called to come out to protest the Senate vote on Wednesday afternoon.

Berlusconi, whose center-right is joined in a fragile coalition with the Democratic Party in Premier Enrico Letta's government, has indicated he will join the opposition if he is pushed out of the Senate. But the government's survival should be guaranteed by Alfano's new party.

Despite his woes, the three-time premier had something to look forward to: a visit by his old friend Vladimir Putin. The Russian president was to dine at Berlusconi's Roman palazzo on Monday night after meeting with Pope Francis and Napolitano earlier in the day.