He said Pakatan Harapan will now ask for an urgent sitting of the Dewan Rakyat.
Speaking to reporters at the Yayasan Al-Bukahry building in Kuala Lumpur, where MPs had gathered to show their support for him, Mahathir said he had no chance to tell the King that Muhyiddin did not have the majority needed to be appointed the prime minister.
“That is the situation now. I cannot communicate with the palace,” he said.
He reiterated that Pakatan Harapan had the majority with “114 MPs who back us, but apparently, that is being ignored”.
On the alleged claim by Muhyiddin that he had the full support of PPBM MPs, Mahathir disputed this, saying six MPs, including himself and his son Mukhriz, did not back Muhyiddin, who is the party president.
He said the law stipulated that the King may appoint someone who he believes has the support of the majority as the prime minister.
However, if the prime minister is rejected in Parliament, then he cannot hold the post, he said, as this was the law.
“But apparently, we are going to see a man who does not have majority support become the prime minister.
“This is a strange thing because the result of the 14th general election should see the winners form the government.
“Here we are going to see from the same election, the losers will form the government while the winners will be the opposition.”
Mahathir said PH will now call for an urgent sitting of the Parliament to determine who has the majority.
Asked if the government to be headed by Muhyiddin would be an illegal one, he said that according to the constitution, Muhyiddin was “not the right prime minister”.
However, there were times when the candidate named by the party that won in the polls was rejected by the King or ruler, he said.
“If the ruler rejects and appoints somebody else and the dewan accepts him, then he becomes the legal menteri besar or prime minister. That is left to the dewan,” he said, adding that “a lot of things can happen” before the next sitting, which could see PH MPs defect to the other side.
Mahathir said he felt “mostly betrayed” by Muhyiddin when asked if he was angry with former PKR deputy president Mohamed Azmin Ali.
“He (Muhyiddin) was working on this for a long time and now he has succeeded.”
He said Azmin had his own agenda but chose to work with Muhyiddin instead.
Asked if he had any regrets resigning as the prime minister, he said: “I had no choice”.