It is possible that Agong Tuanku Mizan Zainal Abidin may not appoint Najib Abdul Razak as prime minister despite being Umno president, said Tengku Razaleigh Hamzah.

Razaleigh, a veteran Umno leader, pointed to last year's decision by the king, who is also Terengganu sultan, in refusing to endorse the Umno leadership's nominee Idris Jusoh as menteri besar for his state.

Eventually Umno backed down and the king's choice, Ahmad Said, became menteri besar.

"He (the king) could probably appointed someone other than the man nominated by the party," said Razaleigh, a Kelantan prince and uncle of Sultan Ismail Petra.