Centre-left challenger Walter Veltroni conceded defeat to centre-right chief Silvio Berlusconi on Monday in Italy's general election.
Veltroni, a former Rome mayor who heads the centre-left Democratic Party (PD), told a press conference he had phoned Berlusconi to congratulate him.
The move followed projections based on the vote results which showed the two-time premier had won a solid victory in both the House and the Senate.
''The election result certifies that the right will govern this country... We hope they will do so with respect for certain fundamental values,'' said the 52-year-old Veltroni, an ex-Communist.
But he predicted that Berlusconi, a 71-year-old media tycoon, would have difficulties holding his alliance together.
Berlusconi heads the Freedom of People party (PDL) which is allied with the populist, devolutionist Northern League and the tiny Sicilian-based Movement for Autonomy (MpA).
The PDL itself was created only two months ago when Berlusconi's Forza Italia party merged with the right-wing National Alliance (AN), its long-time ally.
Veltroni argued that the parties backing Berlusconi still held conflicting agendas which could create problems for the new premier.
''The majority will have difficulty in holding itself together. We don't know how long it will last because programme differences remain,'' he said.
Veltroni concluded by saying his alliance would lend a helping hand in tackling institutional reforms required to modernise the country.
Meanwhile, both Berlusconi and AN leader Gianfranco Fini expressed ''deep satisfaction'' at the results seen by the projections in a telephone call with ANSA.
Berlusconi was following the elections from his home at Arcore outside Milan where he arrived early on Monday evening.
