A multi-billion corruption scandal and international criticism have failed to topple Prime Minister Najib Razak. Fresh political opposition isn't expected to work either, analysts say.

Malaysia saw the birth of its newest political party, the Parti Pribumi Bersatu, last week. With former premier Mahathir Mohamed as founding chairman and former deputy PM Muhyiddin Yassin as president, it's widely believed the party has one clear goal.

"It's explicitly clear that the party [commonly referred to as Bersatu] was created to topple the PM," said Oh Ei Sun, Najib's former political secretary from 2009-2011 and a current senior fellow at Nanyang Technological University in Singapore.

Indeed, it's no secret that Mahathir—once a mentor to Najib—and Muhyiddin are the PM's biggest critics.

Last June, the PM was accused of receiving $681 million in his personal bank account from state wealth investment fund 1MDB, sparking calls for his resignation, led by Mahathir at home and anti-graft watchdogs abroad. Meanwhile, Yassin was sacked last year for criticizing Najib's handling of the scandal.

Early this year, Mahathir rounded up Najib's political enemies to spearhead the 'Save Malaysia' movement-- a campaign to oust Najib and form a national consensus on institutional reforms and a new political system. In March, the movement got more than 1 million people to affirm their concerns over Najib's leadership by signing a document called the Citizen's Declaration and Bersatu's launch is seen as an extension of these efforts.

But with general elections expected in 2018, pundits are sceptical of Bersatu's ability to dislodge Najib's ruling party—the United Malays National Organization (UMNO)—and its coalition government, the Barisan Nasional (BN).

UMNO has helmed Malaysia since independence in 1957 and provides the PM with support of its central leadership and regional chiefs, widely seen as the key to Najib's political survival. In February, Mahathir quit UMNO, saying it was "supporting corruption" under Najib's reign.

Given UMNO's deep roots and historical dominance, Bersatu may not be a formidable enough opponent, suggested Tringh Nguyen, Asia Pacific economist at investment bank Natixis. "It is doubtful that this new political vehicle is going to do much given Mahathir's age [91] and also waning political clout...it's unlikely that Mahathir can galvanize support to topple Najib."

Moreover, Malaysia's fractured political landscape is another obstacle.

"There are many challenges facing Bersatu, especially with the opposition disunited," said Norshahril Saat, fellow at the ISEAS Yusof-Ishak Institute, a research group specializing in Southeast Asian studies.