Silvio Berluscon will christen his new People of Liberties (PDL) party early next year when centre-right, rightwing and smaller local components merge, the first formal meeting of 100 'constituent' workers decided on Wednesday.
''Work quickly and work for the future,'' the premier told the delegates in an old Roman temple in the centre of Rome.
''We're going to change the history of Italy.''
The 100 members of the constituent panel - 50% from Berlusconi's Forza Italia (FI) party, 30% from the rightwing National Alliance (AN) and 15% from local parties such as the southern-based Movimento per L'Autonomia (MpA) - agreed to draft a founding charter to put to a Constituent Assembly in January or February.
AN will hold its last party congress to disband and dissolve into the larger entity shortly before the Assembly.
FI has not yet decided whether it will hold a final congress.
The Northern League, the nascent PDL's ally in a sweeping general-election win in April, is not joining the party.
The new party will be organised through political clubs and the Web like FI was when Berlusconi created it to fill a hole left by scandal-hit centre parties and win power in the early 1990s.
''That way millions of people can be contacted again and again, consulted and regularly involved in the new party's life,'' said the FI pointman for the process, Denis Verdini.
The PDL aims to change Italy's European electoral law before the elections on June 4-7, the first test for the united party.
The unified party will formally ask to join the European People's Party (PPE) caucus, where FI is already represented.
FI officials have said the full-fledged merger will be open to former ally the UDC, a centrist Catholic party now in opposition and a member of the PPE.
Party officials say one of the PDL's main aims is to establish a fully fledged two-party - rather than simply 'bipolar' - system in Italy, with the PDL opposed by a major centre-left party, the Democratic Party (PD).
The PD was largely credited with forcing its centre-right rivals to rally ahead of the April general election by being the first to carve out a single party from centrist Catholic and centre-left elements.
But Berlusconi was in no mood for compliments Wednesday, calling PD leader Walter Veltroni ''non-existent'' and saying there was ''no hope'' of dialogue on institutional reform.
A PD spokesman accused the premier of being ''in a bad mood''.
Berlusconi said Wednesday that the government's first moves, including an immigration and crime crackdown, had boosted its support.
He claimed the opposition would be in the political wilderness for years.
Nationwide, the PDL already operates in virtually all respects as a single party.
But FI and AN still hold separate events and are often represented separately at the local and regional level.
