Muhyiddin Yassin may no longer be deputy prime minister after being jettisoned in a cabinet reshuffle today - but he remains as deputy Umno president, and one who wields substantial influence on the party.

All eyes will now be on whether Muhyiddin will rally his forces against Prime Minister Najib Abdul Razak after being unceremoniously dropped for criticising 1MDB.

With Najib having postponed the Umno elections due next year by 18 months, there is also no way to remove Muhyiddin as the party's deputy chief, other than to sack him from the party.

But even before Muhyiddin is to make any move against Najib, he has to first evaluate the strength of his support, Institute for Democracy and Economic Affairs chief executive Wan Saiful Wan Jan said today.

"If he can gather enough numbers, he can call for an extraordinary general meeting in Umno for a vote of no confidence against Najib.

"Or the vote of no confidence can be done in the coming sitting of Parliament (with the opposition's support)," Wan Saiful ( photo ) told Malaysiakini .

However, he noted that Muhyiddin has been reluctant to move against Najib, despite growing discontent since the prime minister's poor showing in the 2013 general election.

Is Muhyiddin bold enough to take the step?

"The question is whether he (Muhyiddin) is bold enough to take the step," said Wan Saiful.

"We must remember that Muhyiddin's removal was done on the basis of his criticism of the prime minister - and that's not quite the same as challenging the prime minister," he said.

Wan Saiful said Muhyiddin may not necessarily have to lead the movement against Najib, but he could among the key leaders in the movement against Najib.

Nonetheless, Wan Saiful said, if Muhyiddin chose to retaliate, Najib’s ministers would undoubtedly react to contain him.

"He may try to remove Muhyiddin as Umno deputy chief through any way possible," said Wan Saiful, adding that this includes sacking Muhyiddin from Umno.

Furthermore, Najib is more decisive in defending his position, compared to his predecessor Abdullah Ahmad Badawi ( photo ), who, despite being aggressively criticised by Muhyiddin, never dropped Muhyiddin from the cabinet.

Wan Saiful noted that Najib had also moved to consolidate his position with the removal of the Attorney-General Abdul Gani Patail, who was coordinating the special task force investigating claims that RM2.6 billion was deposited into his private bank accounts.

This is on top of the appointment of Mohamed Fuzi Harun as the new Special Branch chief.

Wan Saiful said these moves may be to set the table for a crackdown, not only on public dissent but also within Umno, if necessary.

While the signs of whether Muhyiddin would have the courage to challenge Najib remain unclear, the battle has nonetheless escalated to a new level.

The political conflict had previously revolved around verbal attacks but it has now escalated to claim its first casualties, including Muhyiddin and Rural Development Minister Shafie Apdal.