* Renzi ousts party rival Letta as Italian PM
* Florence mayor has never sat in parliament
* Vows to transform Italy but policy plans vague
* Says reforms more important than EU deficit ceiling
By Gavin Jones
ROME, Feb 14 (Reuters) - Italian centre-left leader Matteo Renzi is young, dynamic and has never shied away from a challenge, but his decision to force party colleague Enrico Letta to resign as prime minister is a huge political gamble.
Renzi is certain to be asked by the president to form a government after Letta hands in his resignation on Friday.
The 39-year-old mayor of Florence has never hidden his ambition to lead Italy, but until this week it was assumed that he planned to do so by winning an election, not by a political manoeuvre that polls say most Italians disapprove of.
The new leader of the Democratic Party (PD) presents himself as a straight-talking outsider who despises Rome’s baroque political deals that have seen five of the last seven prime ministers appointed without a direct mandate from voters.
He either decided that he had too much to lose by biding his time or that he has the ability to push through strong reforms to revive a stagnant economy and Italians will soon forgive him.
“Putting oneself on the line right now carries an element of risk, but a politician has the duty to take risks at certain moments,” Renzi told the PD leadership committee on Thursday in his speech asking them to withdraw their backing from Letta.
An opinion poll by the Piepoli institute published on Wednesday showed only 14 percent of voters supported the idea of Renzi taking over from Letta without a vote.
The PD backed its leader, but the overwhelming vote in favour of Renzi’s coup masks deep misgivings within the party.
“This is a gamble that risks damaging not only Renzi, but also the PD and the country,” said Giuseppe Civati, a high profile deputy who was defeated by Renzi in a primary for the party leadership in December.
Renzi will be the youngest head of government in the European Union. Not only has he never run for prime minister but he has never even been elected to parliament and will be the first prime minister not to have a seat since former central bank governor Carlo Azeglio Ciampi in 1993.
Having gained power without a direct mandate, Renzi knows he will be even more criticised if his government flounders. Yet one thing he has never lacked is self-confidence.
Recognised as a superb communicator, he cultivates a youthful image, likes to talk and dress casually and is often described as brash, cocky and lacking in substance.
Known for arriving at public events in Florence on his bicycle, Renzi prefers to gulp down coca-cola and pizza rather than dine in the discreet Rome restaurants traditionally favoured by senior Italian politicians.
In a popular impersonation by Italy’s best-known comedian, Renzi captivates his audience with a mesmerising sequence of catchy but totally meaningless phrases.
Renzi espouses market-friendly policies like reducing public spending and taxes, cutting red tape and easing firing restrictions. He has also said that while pursuing structural reforms Italy should allow its budget deficit to exceed European Union limits.
He is backed by a large part of Italy’s industrial and financial elite, though he has no experience of national government and his policy prescriptions remain vague.
Since his landslide victory in the PD primary in December Renzi, a former boy scout who began his political career in a now defunct Catholic centrist party, has never been out of the headlines.
He moved fast to try to broker a cross-party deal on a reform of electoral rules blamed for Italy’s chronic political instability, and those proposals are now before parliament.
He has also shown considerable steel in consolidating his grip on the PD by facing down internal dissent from the leftist arm of the party which has always campaigned against him.
But at the same time he systematically weakened Letta and his government with constant sniping from the sidelines, blaming the prime minister for moving too slowly to reform the euro zone’s most sluggish economy over the last decade.
Renzi could hardly be more different from the solid but dull Letta and the two men have a thinly veiled disdain for each other despite both coming from the centrist, Catholic arm of the PD rather than the larger left-wing component.
It was widely thought that Renzi wanted to broker a deal on electoral reform and then win an election in 2015 - when Letta had repeatedly hinted he would step down - at the head of a strong majority that would allow him to govern effectively.
His change of strategy suggests he either thinks he can do better than Letta at the head of the same fragile left-right coalition, or he believes he can change the coalition to include parliamentarians from parties currently in opposition.
He has appealed to lawmakers from the anti-establishment 5-Star Movement to abandon their hard line opposition and support PD legislation.
Renzi is certainly not afraid to make enemies and rode roughshod over protests from shopkeepers and motorists to pedestrianise the historic centre of Florence.
He may find it much harder to trample down the web of political resistance and vested interests that have hampered economic reform at the national level for decades.