Shortly after receiving word in early May that the Malaysian government had cancelled his contract to develop the multibillion-dollar Bandar Malaysia real estate project, a shaken Lim Kang Hoo scrambled to secure a meeting with Prime Minister Najib Razak in the hope of reversing the situation.

Datuk Seri Najib refused to meet the Malaysian businessman or representatives of Mr Lim's Chinese partners, China Railway Engineering Corp.

Instead, Mr Najib dispatched Tan Sri Bustari Yusof to advise Mr Lim, the controlling shareholder of Iskandar Waterfront Holdings. Mr Lim was told that challenging Kuala Lumpur's decision would only dim his chances for future government contracts, according to close associates of the Prime Minister with knowledge of the situation.

"The fact that the message was delivered by Mr Bustari showed that the PM was very serious about the warning that Mr Lim would be blackballed if he did not stand down," said a senior Kuala Lumpur-based banker close to Mr Lim.

In Malaysia these days, one ignores the soft-spoken Mr Bustari, 65, at one's peril.

According to politicians and businessmen supportive of the Najib administration, Mr Bustari's position as senior political counsel, chief troubleshooter and economic adviser is unparalleled in the premier's very tight circle of operatives.

"He is the only person who straddles both business and politics within the inner circle, and what he says matters very much to the PM," said a senior Kuala Lumpur-based businessman, who is close to Malaysia's political elite.

"He would easily count as one of the PM's closest friends. They play golf (together) regularly and Mr Bustari often goes for holidays with the (Mr Najib's) family," noted a chief executive of a government-controlled commercial bank who knows Mr Bustari.

Despite his much-envied clout, Mr Bustari is not widely known among Malaysians.

But that is about to change soon because of his growing business interests and his position as the No. 1 go-to person who can make things happen in the Najib administration.

Mr Bustari declined requests to be interviewed for this article.

But the following account, based on interviews with politicians, businessmen and civil servants, shows how relationships forged in the early years are paying off big time for the businessman from Sarawak.

Mr Bustari's ties with Mr Najib date back to the 1980s when he was a colleague of the premier's influential wife, Datin Seri Rosmah Mansor. Both of them worked in property development firm Island & Peninsular.

During that time, Mr Bustari was already dabbling in politics in Sarawak.

His big break came in 1987 when he made a gamble to back then Sarawak chief minister Taib Mahmud, who was at the time caught in a power struggle for the state's leadership. When Tan Sri Taib, who is currently Sarawak's governor, emerged victorious, there was no looking back for Mr Bustari.

According to several Malaysian politicians, Mr Bustari continued to maintain close ties with Mr Najib, who was then steadily making his way up in the ruling party Umno and in government.

After Mr Najib assumed the premiership in early 2009, Mr Bustari slowly began getting involved in national politics. His strong political connections with the Sarawak leadership made him a particularly important asset for Mr Najib in managing the often-prickly federal-state relations.

Sarawak's role has become more important over the last decade because of Malaysia's fractured political landscape. The 25 elected lawmakers of the governing Barisan Nasional coalition form a critical bloc in Parliament that keeps the coalition in power.

According to several close associates of the Prime Minister, Mr Bustari has been crucial in keeping relations between the Najib administration and the Sarawak state government on an even keel.

All these connections have helped Mr Bustari, whose brother Fadillah Yusof is the Works Minister in Mr Najib's Cabinet, become a very wealthy man.

Mr Bustari's corporate flagship, OBYU Holdings, has extensive holdings in property and plantations in Sarawak. More recently, he has diversified into the construction, healthcare, and oil and gas exploration sectors.

Public-listed Petra Energy, in which Mr Bustari's private corporate vehicles own a collective 27.5 per cent interest, is a major beneficiary of marginal oil fields that were awarded to private players in the deep waters off Sarawak's coast.

Another shareholder in the company is Mr Najib's younger brother, Datuk Mohamed Nizam Abdul Razak, who controls a 9 per cent interest.

Through his Metrocare Services, Mr Bustari and his partners have a 10-year concession to operate and manage hospital support services in all government-run medical facilities in Sarawak.

But most lucrative of all is the role that Mr Bustari's corporate interests are expected to have in the construction of the RM27 billion (S$8.7 billion) Pan Borneo Highway that will connect Sabah and Sarawak.

Contracts are currently being awarded for the 1,090km-long stretch and construction industry executives have noted that one way around trying to secure a piece of the action would be to forge ties with parties linked to Mr Bustari.