Former deputy prime minister Muhyiddin Yassin and former prime minister Dr Mahathir Mohamad are planning to use a two-pronged strategy against Prime Minister Najib Abdul Razak, according to a political insider.

The first part entails convincing the grassroots and the 30,000 branch chiefs to abandon the prime minister, said an Asia Sentinel report today.

This would include distributing books and pamphlets detailing corruption as well as holding ceramahs for the grassroots members.

The second part is more long-term - preparing for the party elections due to be held in 2018.

While a pro-Najib blog had claimed that there was a '5M' splinter cell headed by Muhyiddin seeking to oust Najib in the upcoming party elections, its existence has been denied by Kedah Menteri Besar Mukhriz Mahathir, one of those implicated.

Despite that, this two-pronged strategy to take on Najib might cause the most dangerous rift in Umno since the party feud in the 1980s following a power struggle between Mahathir and former finance minister Tengku Razaleigh Hamzah.

This is because this time, Muhyiddin's forces are purportedly trying to sow apprehension of Najib and the party's leadership among the members.

"I think Umno is finished. The party is wrecked," said a source to Asia Sentinel .

Muhyiddin was completely silenced at the Umno annual general meeting (AGM) last week, though he held an event the day before the official start of the AGM, which drew 1,000 people.

Mahathir and ousted former rural and regional development minister Mohd Shafie Apdal were among those who attended the Muhyiddin event.

Najib has been plagued by scandals involving his brainchild 1MDB and the RM2.6 billion found in his personal bank account.

He has consistently denied wrongdoing and insisted the money was a "political donation" from the Middle East.