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 “(hash)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 “(hash)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.

As a sign of his political skill _ or cynicism _ he was able to rally Berlusconi to the cause of electoral reform.

Renzi shuttles between Rome and Florence aboard high-speed trains, which shave the commute between the heart of the Italian capital and the Tuscan cradle of the Renaissance to an hour-and-a-half. .

While in Florence, he scoots between official appointments in the way many Florentines do _ on bicycle.

Click the TV remote, and chances are good that on any given evening you’ll find him, tieless, maybe in a short black leather jacket, snug black jeans and studded leather boots, on some talk show, with just a trace of a disarming lisp, pushing his agenda, pitching for popular support.

Months before he took 68 percent of the votes in December’s Democratic primary for party leadership, Renzi paraphrased Blair, the former British Labor leader and prime minister. “I adore one of his sayings,” Renzi said. “I love all the traditions of my party, except one: that of losing elections.”

An opinion poll, commissioned by state TV a few days after the breakthrough Renzi-Berlusconi meeting, and whose results were released on Feb. 3, found that 53 percent of Italians would favor a Renzi-led government now without even holding elections.

Letta’s government would have to collapse and Italy’s president refuse to dissolve Parliament for that scenario to be possible, neither of which seem imminent.

So a crucial question arises: how long can Renzi’s rising star keep rising before it peaks?

“He has to keep the reform momentum on,” Piccoli said.

To do so, Piccoli and other analysts say, Renzi must quickly develop his recipe to revive Italy _ not just preach electoral reform. For example, Renzi has been hawking what he calls, in English, his `’Jobs Act,” to chip away at youth unemployment. But he has yet to deliver details.

With reform likely to take a couple months before finally becoming law, the potential for Renzi’s `’biggest stumble is if Berlusconi pulls out” of the deal, said Roberto D’Alimonte, a political analyst and LUISS university professor who helped the mayor craft the reform proposal. `’He knows Berlusconi can make a fool of him.”

Berlusconi has openly admired Renzi as his only formidable political rival: “With courage and even a trace of arrogance that he wants to `rottamare’ all the old party champions,” Berlusconi recently told Corriere della Sera. “And he did it.”

And in perhaps tacit acknowledgement that the perma-tanned ex-premier with a penchant for face-lifts can’t compete with Renzi in the image category, Berlusconi _ perhaps now opting for the elder statesman look _ let himself be photographed recently without his usual heavy make-up.

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Follow Frances D’Emilio at http://www.twitter.com/fdemilio