And there is a risk that political upheavals could delay delivery of government support measures for an export-focused economy that has been hit hard by the coronavirus pandemic.
If this person is Anwar, he will be sworn in as 9th prime minister of Malaysia.
Muhyiddin outmanoeuvred Mahathir and succeeded in forming a coalition dominated by the country's Muslim majority that included Najib's party, and was appointed premier by the king without an election. The move led to the resignation of 95-year-old Mahathir as prime minister.
Muhyiddin also unveiled an additional economic stimulus package worth 10 billion ringgit ($2.41 billion).
If Anwar finally succeeds in winning power it would mark the culmination of a 22-year long struggle, during which he spent nearly 10 years in jail.
"Conclusively we have a strong, formidable majority", he said, but did not reveal the number of lawmakers backing him.
Mr Anwar wouldn't say how many lawmakers his government would command, but said it was "convincing". "With these numbers, Muhyiddin has fallen as PM".
Anwar Ibrahim speaks during an interview with Reuters in Petaling Jaya, Malaysia, February 6, 2020.
Financial paper The Edge reported that Mahathir downplayed Anwar's announcement, quoting the former leader as saying this was not the first time his on-again off-again ally had claimed to control a majority.
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Anwar said he commanded support from close to two-thirds of the legislature's lawmakers.
Ahmad Zahid Hamidi, Umno president and member of Parliament for Bagan Datuk, claims to have been told that a big chunk of Umno and Barisan Nasional MPs have voiced their support for Anwar.
Scenario A: Muhyiddin requests that Parliament be dissolved and the Agong grants the request.
Anwar said he has been granted an audience with the king but it has been postponed as the king is in the hospital for treatment.
Analysts said elections were more likely to end the political uncertainty. The new government, he said, will represent "all people, from Malays and Bumiputeras to others" and hold firm to the principles of the Federal Constitution. Muhyiddin came to power in March, and his opponents have accused him of grabbing power by shifting alliances instead of earning it through votes.
Anwar's statement is set to push Malaysia into another round of political turmoil after the country already underwent two shock government changes in recent years. Anwar had been the anointed successor to long-serving prime minister Tun Dr Mahathir Mohamad until they fell out and Anwar was sacked, subsequently convicted of sodomy and jailed in 1998.
Does this mean Anwar becomes prime minister?
Anwar has described all the charges brought against him as a plot to destroy his political career.