The party leader, Walter Veltroni, astounded his longest-serving parliamentarian by replacing him with a 26-year-old woman.
Yet appeasement has a strong appeal to Mr Veltroni, who is in a vulnerable position.
ECONOMIST: Walter Veltroni risks being too nice to Silvio Berlusconi
Wily Mr Prodi, with Mr Veltroni beside him, turned out to be no mere puppet.
ECONOMIST: D’Alema and Veltroni, rivals on Italy’s left | The
But, although demonstrably willing to innovate, Mr Veltroni has none of Mr Obama's inspiring rhetorical skills.
ECONOMIST: Italy's election: Promises, but no delivery | The
Mr Veltroni is widely thought to have done a good job running Italy's chaotic capital.
To meet Mr Berlusconi's attacks on the Prodi administration, Mr Veltroni is, like his opponent, offering to cut taxes.
ECONOMIST: Italy's election: Promises, but no delivery | The
Mr Veltroni's resignation was a tacit acknowledgment that his 14 months as leader have been an almost unmitigated failure.
With the rank and file behind him, Mr D'Alema fended off Mr Veltroni.
ECONOMIST: D’Alema and Veltroni, rivals on Italy’s left | The
As deputy prime minister, Mr Veltroni took a lot of credit for Italy's inclusion in the single currency's first round.
ECONOMIST: D’Alema and Veltroni, rivals on Italy’s left | The
"Safeguarding Rome's ancient legacy does not mean that the contemporary city is unable to produce artistic beauty, " says Rome's mayor, Walter Veltroni.
Mr Veltroni retorted that he was not about to mortgage the government.
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The centre-left opposition, which recently dumped Mr Veltroni, is making little headway.
Instead, he was ready to discuss with Mr Veltroni a new electoral system along German lines: proportional representation, with a threshold for parliament.
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In part the fact that Mr Veltroni, a former mayor of Rome, was unconvincing in his claim to represent a new kind of politics.
Even before the election, Mr Veltroni said he wanted to co-operate with Mr Berlusconi on electoral and constitutional reforms to make Italy easier to govern.
ECONOMIST: Walter Veltroni risks being too nice to Silvio Berlusconi
Though 19 years younger than the prime minister-elect, who is now 71, Mr Veltroni was already a seasoned politician when Mr Berlusconi entered political life in 1994.
And the left did conspicuously well in Rome, whose mayor, Walter Veltroni, is one of the few credible alternatives to Mr Prodi as leader of the opposition.
Mr Veltroni was particularly shaken last week, when his party colleague in charge of the regional government in Emilia-Romagna, a bastion of the left, defected to Mr Prodi.
Mr Veltroni was, it is true, constantly undermined by Massimo D'Alema, a PD baron and former prime minister whose refusal to take a back seat weakened the centre-left.
The outgoing finance minister, Tommaso Padoa-Schioppa, put up tax rates while cracking down on tax evasion a combination that made the government hugely unpopular, and damaged Mr Veltroni's campaign.
It was particularly striking that Mr D'Alema and his party's national secretary, Walter Veltroni, were both overshadowed at the conference by a third man, Sergio Cofferati, the old-style boss of Italy's largest trade union.
The main rival to the 58-year-old Mr Bersani was Dario Franceschini, a former Christian Democrat who stepped in when the previous leader, Walter Veltroni, resigned in February after a disastrous showing in a regional election.
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In the early stages of the ten-week campaign, Mr Veltroni sought to latch on to developments in America by depicting himself as Italy's Barack Obama: the man who would surprise everyone by coming from behind.
ECONOMIST: Italy's election: Promises, but no delivery | The
Yet although Italian bondholders took a hit from the subsequent default and Italy's economy was soon overtaken by Spain's, financial markets proved forgiving, and the government of Walter Veltroni managed to rejoin the euro fairly quickly.
Mr Veltroni's hopes rest on two factors.
ECONOMIST: Italy's election: Promises, but no delivery | The
But the rivalry goes much further back, to the days when Mr D'Alema studied the subtle Marxist strategies of Antonio Gramsci, while Mr Veltroni, though barred from the United States because of his red label, was idolising Robert Kennedy.
ECONOMIST: D’Alema and Veltroni, rivals on Italy’s left | The
Others on the centre-left, for instance Mr D'Alema's Blairite colleague, Walter Veltroni, are again bemoaning the effectiveness, and unfairness, of Mr Berlusconi's ready access to the air-waves: the tycoon-cum-politician happily floods his own television channels with advertisements in praise of himself.
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