Prime Minister Muhyiddin Yassin's last-ditch concessions to secure bipartisan support at next month's confidence vote in Parliament has upped the ante on Malaysia's opposition.

Even though leaders of the 105-strong opposition and Umno president Zahid Hamidi's camp of about 15 lawmakers rejected the offer out of hand, they have yet to unite behind opposition leader Anwar Ibrahim, or any other MP, as the successor to the Premier.

Furthermore, no one has articulated a better proposal than what the Premier has on the table.

Tan Sri Muhyiddin said on Friday that if he wins the confidence vote, he will make six reforms, and a seventh if he gets a two-thirds majority.

These include allocating equal constituency funds to all MPs, adding RM45 billion (S$14.4 billion) to the Covid-19 fund as mooted by the opposition, according to Datuk Seri Anwar the same standing as a senior minister, as well as electoral and parliamentary changes such as limiting a premier's tenure to two terms.

Just hours before his address on Friday, the 88-strong Pakatan Harapan (PH) headed by Mr Anwar had invited an estimated 120 out of 220 federal lawmakers opposed to Mr Muhyiddin's rule to negotiate terms for a new Anwar-led government.

"This is the PH stance, to have (only) one candidate from PH to avoid confusion due to rumours of negotiations to nominate someone else. But this does not preclude us from working with all parties," said Mr Anwar, who is also Parti Keadilan Rakyat president.

But senior PH strategists told The Sunday Times that it was exactly this lack of alternatives to Mr Muhyiddin that triggered the invitation for other potential candidates. Outside of the pact, few of the MPs opposed to the Prime Minister have faith in Mr Anwar's leadership.

While Zahid has worked hand in hand with Mr Anwar in recent months to topple Prime Minister Muhyiddin, Umno has resolved that it would not ally with its long-time foe.

Umno MP Tengku Razaleigh Hamzah, Malaysia longest-serving lawmaker, is seen as a compromise candidate, but Mr Anwar's camp is unwilling to play second fiddle.

Many in PH are also staunchly opposed to forming a government with Umno, having vilified the once dominant party as being riddled with corruption and racism.

"We need to present someone with a majority before the vote, otherwise we will see a repeat of the Sheraton Move," a top PH official said on condition of anonymity due to the sensitivity of internal discussions.

The Sheraton Move refers to the shock end of the PH government's 21-month rule early last year. Then Premier Mahathir Mohamad resigned after refusing to go along with plans by rebels from his Parti Pribumi Bersatu Malaysia and PKR to form a government with the Umno-led Barisan Nasional, as it would mean working with his predecessor Najib Razak and Zahid who faced graft charges after their defeat at the 2018 polls.

Instead of presenting an outright majority, Mr Anwar banked on having the largest bloc with 92 lawmakers, while others were split between having Tun Dr Mahathir as premier again or a snap election.

Eventually, Bersatu president Muhyiddin was sworn in as Premier, after cobbling together his Perikatan Nasional (PN).

Today, the ruling pact numbers about 100 and Mr Muhyiddin needs the support of 111 lawmakers.

But time is not on his side, with Parliament set to reconvene for the confidence motion in three weeks. And following the offer of concessions to the opposition, some Umno MPs are now fuming over the possibility of having to work with Mr Anwar, believing it will hurt their standing in the party.

On the opposition side, Mr Muhyiddin's olive branch has been brushed aside and he has been accused of hypocrisy and lack of sincerity. They said a confidence-and-supply deal had been on the table since last year - confirming The Straits Times' report in November - and that the Premier was usurping the King's constitutional role by asserting that no other MP had a majority.

Moreover, most of the reforms proposed were already part of PH's manifesto, although they were not carried to completion during their time in power.

But while these attacks may be justified, analysts believe they deflect from the central issue.

"The point is whether he will be forced by circumstances to deliver on his promises. Muhyiddin is giving Anwar and Tengku Razaleigh a run for their money with two challenges - to forge a majority and a better deal of reforms," said political scientist Wong Chin Huat.

"He is not sincere, but sincerity here is not the point. If they can match the offer made by Muhyiddin then whatever Muhyiddin offers becomes insignificant," said the professor from the Jeffrey Cheah Institute on South-east Asia.

A small number in the opposition who are staunchly against joining hands with Zahid and Najib's faction believe they can demand more reforms from PN. They also want the demands to be tabled in Parliament alongside the confidence motion, thus allaying concerns about Mr Muhyiddin's sincerity or the risk that he will not follow up on his concessions.