Former premier Dr Mahathir Mohamad has ended numerous political careers over the decades but appears unable to dislodge Prime Minister Najib Abdul Razak.

Umno information chief Annuar Musa believes that he knows the reason behind Mahathir's failure to do so.

"I was having dinner with the prime minister at his home last night, just four or five of us. We discussed why Najib has not fallen despite Mahathir believing that he can topple him.

"He wanted to topple Ku Li (Tengku Razaleigh Hamzah), Musa (Hitam), Anwar Ibrahim, Pak Lah (Abdullah Ahmad Badawi)... they all fell.

"But anything he does against Najib has failed. Why?” he asked during the Umno convention on information and media at the Putra World Trade Centre in Kuala Lumpur today...