A refusal by the leading anti-corruption prosecutor, Antonio Di Pietro, to take the powerful Interior Ministry portfolio deflated hopes that Mr Berlusconi might hand a list of ministers to President Oscar Luigi Scalfaro today.
The delay is likely to embarrass Mr Berlusconi, whose slow progress in putting together a government drew criticism from the outgoing and now caretaker prime minister, Carlo Azeglio Ciampi.
Umberto Bossi, the federalist Northern League leader, had insisted that their candidate be the interior minister because that ministry controls local authorities.
Faced with Mr Berlusconi's refusal to hand over the interior min istry, which also runs the police and secret service, the League reluctantly agreed to Mr Di Pietro, who has become a national hero because of his role in the Mani Pulite (Clean Hands) investigations. But Mr Di Pietro turned the job down.
Francesco Speroni, the League's leader in the Senate, voiced his discontent on television: 'Berlusconi wants to play the magician. Now let him pull a rabbit out of the hat.'