PKR president Anwar Ibrahim, who claims to have the support of MPs to form a new government, said he does not have the backing of Dr Mahathir Mohamad and the latter's new party Pejuang.
"(Mahathir might) decide later (to support) but now, no," he told a press conference in Kuala Lumpur this afternoon.
Asked specifically if the four other Pejuang MPs are supporting him, Anwar replied, "Belum" (not yet).
Mahathir is the MP for Langkawi.
Quizzed if the so-called new government would need a "new manifesto", Anwar said the matter would be discussed with the "new coalition".
"The principles of integrity, anti-corruption, judicial independence, propelling economic growth and social equity must be stressed," he added.
Earlier, Anwar declared that Muhyiddin Yassin's reign as prime minister had come to an end because he had secured a "solid and convincing" majority support from among the 222 MPs.
However, the opposition leader refused to reveal the list of MPs who purportedly supported him but dropped hints that he had secured the backing of individual MPs rather than parties.
So far, only Amanah, which has 11 MPs, has come out to state their support for Anwar.
Anwar said his audience with the Yang di-Pertuan Agong was scheduled for Sept 21 at 11am but had to be postponed because the king had to undergo medical treatment.