Cameroon's Paul Biya at helm of poll winning machine

"Today, it is impossible to imagine a scenario where Biya gives up power in a conventional way or naturally before the end of his mandate," said Stephane Akoa, a researcher with the Paul Ango Ela Foundation think tank.

"As long as he can run for a mandate, I don't see anything to stop him doing so."

Biya prepares for another seven in years office after an October 7 ballot marred by allegations of fraud, low turnout and violence in the country's Anglophone regions, where a separatist insurgency is testing his government.

One aspect of his time in office is the "subtle balance of forces" which Biya has created in the country, in a region where leadership changes are often accompanied by force, according to International Crisis Group's (ICG) Hans de Marie Heungoup.

Cameroon's system was "designed so that everyone polices themselves and maintained inter-generational and ethnic rivalries," Heungoup said.

"No one can move an active (security force) unit without the say-so of the president," he said, emphasising the importance of the balance between the regularly army, the rapid intervention force, and the presidential guard -- the last two of which report directly to the president.

The president's appointment of loyalists to key posts has also assured his long rule.

"Those who want power don't last, it's those who can (rule)" Biya told journalists in 2015, making a rare remark about his long time in charge of Cameroon.

'You'll be crushed'

The speaker of the National Assembly, the head of the army and the head of the state-run oil and gas company are all confidants of the president, and have each held their jobs for more than 15 years.

The system has been strengthened through "a mix of resigned acceptance and patronage among certain elite leaders who rally behind the regime," said Fred Eboko, a researcher at the French Institute for Research and Development (IRD).

Biya's primary motivation since coming to office has been "to stay in power," he added.

"The system is built on a single individual and this individual is identified with the job," said Titus Edzoa, a former confidant of the president who was secretary general of Biya's presidency between 1994 and 1996 and held ministerial posts on several occasions.

"If you try to go against Biya, you'll be crushed," he said.

'In power for 35 years... that's talent'

Edzoa should know. After resigning as a health minister in 1997 to stand in elections, he was arrested and accused of stealing millions of CFA francs. He spent 15 years behind bars.

Now a free man, he warns that by centring the system on Biya's personality "not only could the system implode, but so too could the whole of Cameroon" in the near future.

"Whether you want him or not, he's still human and you have to think of the future," he said.

"How do you look back on the story of a people dominated by an individual?"

Biya survived a coup attempt in 1984, which permanently scarred him, a security official in Yaounde said.

"Before he would step out in Yaounde, he was close to people. But imagine, he was stuck for hours in a bunker and there were bullet marks all around when he emerged. That leaves a mark," the source said.

His repeated long absences from Cameroon, mostly in Switzerland or in his home village in his country's south, have been bitterly criticised.

According to the Organized Crime and Corruption Reporting Project (OCCRP), a consortium of investigative journalists, Biya spent "at least four-and-a-half years of his 35 years in power on private visits" abroad.

But for the final leg of the campaign, Biya did at least make a rare public appearance, visiting the far-north which has been engulfed by Boko Haram jihadist violence -- his first trip there since 2012.