ROME (AP) — He’s a brash, kid-faced dynamo who is injecting fresh blood into Italy’s sclerotic politics — and the left’s great hope now that Silvio Berlusconi’s criminal convictions keep the long-time leader out of power.

And Matteo Renzi, elected in December as leader of the Democratic Party, has even cut a deal that many would have thought impossible.

Who would have bet that the Communist-hating Berlusconi would have done business in a room where Fidel Castro and Ernesto Che Guevara gaze down from photographs on the wall?

The irrepressible Renzi did.

The 39-year-old Renzi, who cites Tony Blair as a hero and doubles as Florence mayor when he isn’t running Premier Enrico Letta’s center-left party, has confidently, almost cockily, established himself as the politician to reckon with these days in Italy.

His eyebrow-raising invitation to the former premier last month for a tete-a-tete in the den of his enemies — the Democratic Party has deep roots in Italian Communism — was a typical Renzi gamble.

With characteristic flippancy, the youthful Florentine brushed off hostility from within his own party for his courting the scandal-stained leader of Italy’s main center-right party.

For Renzi, it was just realpolitik to negotiate with the Democrats’ archrival in what turned out to be a successful bid to nail down Berlusconi’s crucial backing for elusive electoral reforms aimed at finally making Italy more governable.

‘‘Who was I supposed to meet, Dudu’?’’ Renzi asked — referring to the white poodle that Berlusconi’s fiancee totes around like a fashion accessory.

Bluntness like Renzi’s is a novelty in a country whose language lends itself to the kind of convoluted phrasing politicians frequently take refuge in.

But then, much about Renzi is different as he positions himself for a bid to be premier and to replace Berlusconi as Italy’s dominant political player. Elections aren’t due until 2018 — but no one expects Letta’s nine-month-old fragile government that relies on defectors from the Berlusconi camp, to last more than another a year or so. Letta’s fall would open the way for Renzi to make his power play.

One of the keys to Renzi’s appeal is that he’s never been in Parliament — making him a refreshing outsider for many Italians.

Parliament is where the wheeling and dealing are done to cobble together Italy’s coalition governments or hasten their demise. His entire political career — until rank-and-file Democrats overwhelmingly picked him in a primary to be party leader — had been in the relatively small city of Florence, first as province president and now as mayor.

With roots in pro-Catholic center-left movements, the former longtime Boy Scout also has never been a Communist, unlike many of his fellow Democratic leaders who cut their political teeth in what had once been the West’s largest Communist Party.

His lack of experience in Parliament — where fisticuffs are not infrequent and where proposed reforms languish while lawmakers draw handsome paychecks — is more asset than liability, at least for now.

‘‘Renzi is a sort of breath of fresh air,’’ said Wolfango Piccoli, an Italian political scientist based in London.

With their country mired in recession, and youth employment stuck around 40 percent, Italians are ‘‘disillusioned with the entire political class,’’ Piccoli said in a telephone interview.

One strong Renzi asset is his language, noted Piccoli. ‘‘You can actually understand what he’s saying. He’s not very polished, but that is a huge advantage’’ in a country weary of politicians who promise a lot and deliver little.

Renzi is a clever and regular communicator on Twitter. A sampling of some recent Renzi tweets range from reassuring fellow Fiorentines during torrential rain to a progress report on his proposed reforms.

Telegraphic as well as telegenic, Renzi has coined two eminently hash-taggable slogans to reach a largely young base. Even older Italians have taken to using his slogans as they chat about politics, on buses, cafes and neighborhood markets.

One is ‘‘#rottamare,’’ a colloquial verb generally used when talking about dumping broken appliances in the junkyard. Renzi says he wants to ditch a generation of politicians ‘‘glued to their armchairs.’’

The other is ‘‘#lavoltabuona’’ — roughly ‘‘this time we can do it,’’ a peppy phrase Renzi tacks on to his ‘‘Let’s change Italy’’ mantra.

Renzi’s big political idea: overhauling electoral law to produce Parliaments that can actually pass laws. Under current rules, tiny parties have disproportionate clout in keeping governments afloat and adopting laws. The plethora of parties often translates into political paralysis — with bills held hostage to the demands of small groupings. Renzi also wants to drastically reduce political costs, notably by downsizing the role of the Senate, the legislature’s upper chamber.Continued…