Almost 20 years ago, then prime minister Dr Mahathir Mohamad was on the cusp of handing power to his then deputy Anwar Ibrahim, having taken a sabbatical and allowing the latter the opportunity to test his mettle in leading the country.

But after a falling out, Mahathir accused Anwar of sodomy and declared him to be "morally unfit" to become prime minister.

With Mahathir named as Pakatan Harapan's prime ministerial candidate today, the 92-year-old may find himself in the same position again if the coalition captures federal power.

Asked about the transition of power to Anwar should Mahathir become prime minister again, the Bersatu chairperson acknowledged the agreement about the jailed PKR de facto leader taking over from him.

"There are processes to go through. Of course, it will be up to the party to determine when he takes over," Mahathir told a press conference after the Harapan convention in Shah Alam today.

Mahathir being named as the prime ministerial candidate today was on condition that the new Harapan federal government, if it comes to pass, will immediately seek a royal pardon for Anwar.

Anwar will be freed from prison on June 8 but faces a five-year ban from politics. He was sent to prison in 2014 for sodomy, a charge he claimed was politically motivated.

If Anwar receives a royal pardon, he can then contest in a by-election and take over from Mahathir.

Mahahir, when asked whether he will serve his full term or halfway before allowing Anwar to take over, was coy.

"It could be anything. I am 92-years-old. I won't last forever," he said.

Regardless of when Mahathir hands over power to Anwar, the irony of handing the reins to a man he once denied the top seat for being "morally unfit" is not lost.

But Mahathir, when pressed about the matter, did not want to dwell on it.

"That was history. The priority now is to topple Umno and Najib," he said...