Italian Prime Minister Silvio Berlusconi gestures during a political party meeting in downtown Milan April 17, 2011. [Photo/Agencies]

ROME - For a politician on trial over charges ranging from tax fraud to paying for sex with a minor, Silvio Berlusconi is notably free of self doubt.

"I think it's positive that I'm here to represent Italy and lead the centre-right," the Italian prime minister said last week in comments at an off-the-record dinner with foreign press that were leaked to Italian newspapers.

"As long as there's no one to replace me, I'll stay for some time longer."

That confidence has been a vital asset in Berlusconi's career, from his early days as a cruise ship entertainer to his success as the head of a vast property and media empire, and his 17-year spell at the top of Italian politics.

Berlusconi's legal problems have once again put his outsize personality in the spotlight, providing plenty of ammunition for his many critics but in certain ways also highlighting his dominance of the Italian political system.

"Berlusconi is a very unusual person," said one senior foreign official who has had extensive contact with the 74-year-old prime minister. "He's very generous, he's also very forceful. He overwhelms people, even physically," he said.

It is difficult to imagine any other western leader surviving the kinds of allegations Berlusconi faces.

He is accused of trying to avoid paying millions of euros in tax, of bribing his lawyer to give false evidence in court and of paying for sex with a 17-year-old and then pressuring police officials in a bid to cover the story up.

But with no credible alternative on the right and a weak and divided opposition on the left, he has variously laughed off the charges or launched vitriolic counter-attacks on the "subversive" magistrates he accuses of trying to destroy Italian democracy.

He also appears completely unembarrassed by quasi-pornographic newspaper accounts of "bunga bunga" sex parties at his palatial house near Milan where magistrates say he entertained a veritable harem of young women.

"My compliments, you are so good you make me want to invite you to bunga bunga," he told two young women as he presented them with awards at a ceremony for young business leaders at Rome University earlier this month.

Pragmatic streak

That kind of remark has been a trademark down the years and helped to create a widespread image of Berlusconi as a gaffe-prone eccentric.

But it disguises a pragmatic streak and a sure feel for personal relations he says is key to his success in dealing with foreign leaders like Libya's Muammar Gadhafi and Russia's Vladimir Putin and has made him Italy's predominant political leader since 1994.

"Berlusconi doesn't have a strategy. He just does things he thinks will produce results," said a senior Italian executive who has had close relations with the prime minister for years.

"He thinks everyone is his friend so he doesn't have any trouble calling people."

At the same time, he has an unshakeable faith in the power of optimism and positive thinking and frequently regales audiences with stories of his own successes in business, politics and life.

"You have to be absolutely optimistic about reaching any goal you set," he told the young business leaders in a homily which ran from risque jokes, fashion tips ("you can't wear a blue suit with brown shoes") to advice about running a company.

Berlusconi's huge fortune, his control of Italy's main broadcasters and a fragmented political system have all helped him through his recent travails, and although his approval ratings have dived, he retains a substantial and fiercely loyal core of support.

"It's completely wrong to say most of the country backs Berlusconi but about one Italian in four does, which is quite a lot," said Luigi Crespi, a pollster and political commentator.

As his troubles have mounted over the past year the optimism has been tested and there has been much speculation about whether his renowned energy has been flagging and his attention diverted by the trials.

Berlusconi has said he might not run again when his term expires in 2013, setting off a flurry of speculation about his possible successor to lead the ruling PDL party.

Few believe, however, a party created around a person like Berlusconi can long survive without him.

"What is a charismatic party without the charisma of its leader?" asked one minister recently.