In another twist to Malaysia's political drama, interim prime minister Mahathir Mohamad said he is back as PM candidate after securing backing of old rival Anwar Ibrahim.

"This morning I had a meeting with leaders of Pakatan Harapan. I am now confident that I have the numbers needed to garner majority support in the Dewan Rakyat," Mahathir said today, referring to Malaysia's House of Representatives, reports The Straits Times.

The Lower House has 222 seats, with 112 needed to form government. PH has 93 lawmakers from three parties - Parti Keadilan Rakyat (PKR), Democratic Action Party (DAP) and Parti Amanah Negara.

The move averted a showdown between Mahathir and Anwar whose relationship has shaped Malaysian politics for two decades, but which risked sidelining both and returning to power the corruption-tarnished former ruling party they had defeated.

Mahathir, who as interim prime minister is the world's oldest government leader at 94, and Anwar, 72, swept to a surprise election victory in 2018, but friction between them continued and was at the root of the latest crisis.

Anwar said he was going to tell Malaysia's monarch that Mahathir was now the prime ministerial candidate of the Pakatan Harapan (Alliance of Hope) coalition, reported Reuters.

Anwar thanked coalition members for agreeing with his decision "to take a step back and to put forward Mahathir as our candidate for prime minister, in order to avoid a political crisis and being thrown into the old system that we rejected".

The political futures of both men had appeared in doubt on Friday, with Anwar competing as a candidate in his own right and Mahathir finding little support for a unity government that would have strengthened his power.

A new alliance had formed behind former interior minister Muhyiddin Yassin, 72, who had the backing of the old ruling party, the United Malays National Organisation (UMNO) and Islamist party PAS.

Mahathir also denied that he supports Parti Pribumi Bersatu Malaysia president Muhyiddin Yassin's candidacy, reported The Straits Times.

"As I had repeatedly stated, I am against any form of cooperation with individuals who are known to be corrupt and was part of the kleptocratic administration which the Pakatan Harapan Government had worked hard to rid off," he said.

It was UMNO's ruling coalition that Mahathir and Anwar united to drive from power in 2018 under then prime minister Najib Razak, who now faces graft charges.

"Pakatan only has one candidate that could win the support of the majority of the MPs, Mahathir not Anwar," said analyst Adib Zalkapli of Bower Group Asia.

"Anwar will have to fight another day. Today is all about stopping Umno and PAS from returning to government."

Still in doubt, however, was Mahathir's backing from his own Bersatu party, which had swung behind Muhyiddin. Mahathir formed the party in 2016 after exiting from Umno.

Bersatu exited PH alliance on Monday and named its president Muhyiddin as its prime minister candidate of choice on Friday.

With the departure of Bersatu's 26 lawmakers from the coalition and the exit of 10 lawmakers from PKR - led by former PKR deputy president Azmin Ali - the PH government collapsed without a 112 MPs majority.

On Monday, Mahathir resigned as prime minister but was made interim PM while lawmakers decide among themselves who can command the widest support to form government.

The past week has seen multiple U-turns, with nearly all political parties with representatives in parliament backing Mahathir as PM on Monday. However, that support immediately fell apart after the 94-year-old pushed for a nonpartisan government, a move that was opposed by parties from both sides.

Umno and PAS retracted their support and began calling for snap polls, while PH came out to back PKR president Anwar Ibrahim as PM candidate. By midweek, neither side could win the numbers game.

By Friday, new allegiances appear as foes began to join hands. Starting with Bersatu stating its support for party president Muhyiddin Yassin as PM candidate. The Bersatu meeting was attended by the party's MPs and the 10 quitters from PKR.

Umno and PAS soon backtracked on their wish to hold elections, and throw their bets on naming Muhyiddin as their PM candidate as well. The Malay-centric partnership was gaining ground with expectations that Borneo parties in Sabah and Sarawak that had previously supported Mahathir would now join hands with Muhyiddin as well.

However, today's statement by Mahathir and PH has given the Malay pact a major setback. PH and Mahathir still do not have the 112 needed, but if Parti Warisan Sabah comes along with its 9 MPs and several from Bersatu follows Mahathir - Malaysia may just come back with a PH government after all.

With Mahathir back in the running, it is unclear who Bersatu will back. Today morning, it uploaded and then promptly deleted a statement backing Mahathir.