(ANSA) - Rome, February 22 - Matteo Renzi on Saturday crowned a swift ascent to Italy's top job on the basis of a strong reform platform which has broad popular appeal.

Renzi, Italy's youngest premier at 39, was sworn by President Giorgio Napolitano on Saturday and confidence votes are expected to back his administration by Tuesday night.

Thanks to his relative youth and lack of national experience, the leader of the centre-left Democratic Party (PD) is seen as representing the kind of generational change that corruption-weary voters just might be looking for.

Renzi, Italy's third straight unelected premier, has been mayor of his native Florence for five years and and has never been a member of parliament - which to many, is a strong advantage in Italian politics, tainted by decades of scandal, pork-barrel policies and political entitlement.

He was defeated in his first bid in December 2012 to take the PD leadership, ending well behind Pier Luigi Bersani, who resigned after he failed to create a coalition government following February 2013's inconclusive general election and two months of stalemate.

Renzi persevered and in December 2013 won a subsequent PD party primary by a landslide.

He continues to ride the wave of strong approval ratings that have led some to compare him to a young Tony Blair, the telegenic former Labour prime minister of Britain who was criticized by some for steering his party away from its leftist roots but drew masses of middle-class voters back after the Thatcher years with his 'Third Way' between progressive social policies and business-friendly economic ones.

The law-school graduate from the University of Florence plays up his youthful and dynamic image, usually appearing on stage in black jeans and a white shirt, cuffs rolled back to indicate his willingness to get down to business.

In a photo spread for the Italian issue of Vanity Fair magazine published shortly before the December primary, Renzi appeared in a similarly styled outfit, demonstrating his preparedness for the hard work of governing Italy.

He is also frequently photographed in dark glasses and a leather bomber jacket, a contrast to the usual buttoned-down designer suits of Italy's political class and the basis of frequent comparisons to legendary TV character Fonzie, the essence of cool.

Similarly, he is often seen riding a bicycle or driving a Smart car, nods to his environmental awareness.

Renzi's ascent has been relatively swift despite claims he has little real-world experience other than a stint working for his family's marketing services firm.

The father of three children and a Catholic Boy Scout for 20 years, Renzi was a Wheel of Fortune winner at 19 and is known for his common touch and fast-talking command of policy briefs - though critics claim he is too fond of sound-bites.

He is often seen dominating political chat shows, while the cameras have followed him in his passions for running and five-a side soccer.

Renzi cut his teeth in the Italian People's Party, the main heir to the Christian Democrat (DC) party that ruled Italy from the war until the Bribesville scandals of the early 1990s.

He joined the PD in 2007 and is seen as having the strongest centrist Catholic roots in the party's leadership history, dominated by post-Communists.

He was distrusted by old-guard leftists but the party swung solidly behind him when he proved his cross-party appeal as the PD's best answer to the centre right's charismatic and unsinkable leader, Silvio Berlusconi, who was only ever defeated by another former Christian Democrat, Romano Prodi, on two occasions.

Renzi first served as president of Florence province, a job he held for five years, before he was elected mayor of the city of Florence itself in June 2009 by a strong vote, almost 50% compared with his rival's 32%.

Only a year after being sworn into that post, Renzi began to talk about the need for great change at the national level, and of the necessity of scrapping the old way of doing business while presenting himself as a voice for a new generation of Italians.

As a result, he was dubbed 'Rottamatore' (Scrapper) or, more recently, Demolition Man.

Since becoming PD secretary two months ago, Renzi repeatedly - until very recently - dismissed suggestions he might also try to scrap Enrico Letta, his PD colleague who had been premier of a roughly crafted coalition government since last April.

Letta, the PD's deputy leader behind Bersani, had been recruited by President Giorgio Napolitano to lead an unprecedented left-right coalition government following last year's post-election deadlock and Bersani's failure to woo the anti-establishment 5-Star Movement of comedian-turned-politician Beppe Grillo, the third force in Italian politics.

Letta steered a tricky path under constant sniping from the other senior coalition partner, the now-defunct People of Freedom (PdL) party of media magnate Silvio Berlusconi, who eventually stormed out after failing to bring the government down when the PD insisted on the three-time premier's ejection from parliament on a tax-fraud conviction.

Letta appeared to making faster progress on much-needed reforms with a more streamlined coalition where the PD was a far bigger partner of the New Centre Right, a new breakaway party from Berlusconi's reanimated Forza Italia (FI) party.

But Renzi recently stepped up criticism of Letta's style, lack of progress on reforms to election law and improvements to the economy, before torpedoing the former premier in a ruthless five-minute speech to the PD executive last week.

Renzi also pulled off a coup in January when he teamed up with Berlusconi to draft a new election law, replacing one that was quashed as unconstitutional last year.

He hailed the deal as achieving in "a week" what politicians had failed to agree on for almost a decade, but the agreement with the left's old enemy drew anger from some in the PD, who accused Renzi of helping Berlusconi rehabilitate his political image after the 77-year-old billionaire's ban from holding office.

The NCD, which is expected to team up with Berlusconi at the next elections despite a recent spat pundits reckoned was phony, reportedly insisted on a justice minister who would uphold the rights of suspects and defendants, especially from wiretapping they and Berlusconi say is intrusive and unnecessary.

It also openly said it had forced Renzi not to try to achieve electoral reform immediately, as he had vowed, but instead link it to wider Constitutional reforms which will take years.