As former finance minister Daim Zainuddin gets smeared in the mainstream media, it appears that the proxy war between former prime minister Dr Mahathir Mohamad and incumbent Najib Abdul Razak is escalating.
 
But with 22 years at the top post and still an influential figure, Mahathir already has much experience in knocking his opponents into the political abyss.
 
Malaysiakini recounts some of those who have been, or still are, on Mahathir's hit list.
 
Tunku Abdul Rahman (1970)
 
Roughly a month after the May 13 riots in 1969, Mahathir penned a letter to then prime minister Abdul Rahman accusing his policies as being pro-Chinese, that Tunku  was directly responsible for the riots, and told him to resign.
 
The letter was also widely copied and circulated to the public, and it struck a chord with other Umno members and Malays.
 
As a result, Mahathir, then an Umno supreme council member, was sacked from the party for indiscipline.
 
For Tunku Abdul Rahman, however, his fate was already sealed and he was forced to resign on Sept 22 the following year.
 
It was also during this period, when he was in the political wilderness, that Mahathir wrote his best-known book, The Malay Dilemma.
 
Musa Hitam (1986)
 
Then deputy prime minister and home minister Musa Hitam resigned in February 1986, ostensibly due to irreconcilable differences with Mahathir.
 
Three months earlier, Musa took the blame for the Memali Massacre in Baling, where 14 alleged religious deviants and four police personnel were killed
 
This took place while Mahathir was said to be abroad, visiting China, and Musa was the acting prime minister.
 
However, Musa revealed last year that Mahathir was in fact in Kuala Lumpur at the time. Mahathir then confirmed this but insisted that the incident occurred under Musa’s watch.

Regardless, with his reputation dented, Musa teamed up with his long-time rival Tengku Razaleigh Hamzah to challenge Mahathir and his new deputy Ghaffar Baba in the 1987 Umno election.
 
Mahathir’s camp narrowly won and proceeded to purge Tengku Razaleigh’s supporters from positions of power, but only to have the court invalidate the party elections due to irregularities and Umno was declared illegal.
 
Nevertheless, Mahathir moved on and established the New Umno (Umno Baru) while Tengku Razaleigh founded his short-lived Semangat 46.
 
Anwar Ibrahim (1998)
 
Now parliamentary Opposition Leader, Anwar was co-opted into Umno in 1982 by Mahathir himself and quickly rose through the party ranks.
 
However a rift grew between the two and Anwar was eventually sacked as Umno deputy president and as deputy prime minister, on Sept 2, 1998, and stripped of his Umno membership.
 
Anward was then charged and convicted of sodomy and abuse of power, although some of these convictions were overturned in 2004.
 
During this time, a smear campaign against Anwar was also run through the media and within Umno itself. Books containing highly graphic allegations against him were distributed at Umno general assemblies on several occasions.
 
Abdullah Ahmad Badawi (2009)
 
Abdullah took over as prime minister after Mahathir resigned in 2003, and he then led Umno and BN to its best electoral victory, in the 2004 general election.
 
In the meantime, Mahathir was not content to watch his successor reverse policies and decisions he made as prime minister, and therefore Mahathir began to criticise Abdullah’s administration.
 
As he was being shut out of the mainstream media, Mahathir turned to blogging and even granted an interview with Malaysiakini to vent his frustrations.
 
A DVD containing a recording of him criticising the government at a closed-door function was also distributed during Umno’s 60th anniversary celebration in 2006.
 
The writing was on the wall for Abdullah when BN shockingly lost five states and most of Kuala Lumpur’s seats to Pakatan Rakyat in the landmark 2008 general election.
 
In May 2008 Mahathir surrendered his Umno membership and vowed not to return until Abdullah resigned.
 
Abdullah stepped down on April 3, 2009, and a jovial Mahathir handed his membership application to the newly-minted Prime Minister Najib Abdul Razak.
 
Najib Abdul Razak?
 
Although grumblings against Najjib had already begun earlier, attacks by Mahathir’s loyalists began to escalate soon after the 13th general election, where BN suffered its worst ever electoral performance, with the opposition gaining over 50 percent of the popular votes despite BN’s slim victory.
 
By August last year, Mahathir too began scathing attacks against Najib, claiming that he was a disappointment and worse than Abdullah.
 
Among his grievances: The 1Malaysia Development Bhd (1MDB) debt scandal, the repeal of the Internal Security Act, the Transpacific Partnership Agreement (TPPA) with the US and economic policies such as minimum wage.
 
Can Najib withstand Mahathir’s onslaught or will Mahathir topple yet another prime minister?

Malaysiakini will continue bring you the latest as this tussle plays out