The late Nigerian President Umaru Yar'Adua came to power in 2007
By Mark Doyle
BBC News, Abuja
The death of the Nigerian President Umaru Yar'Adua has exposed popular anger over the nature of the country's power politics - and, according to one political scientist, revealed the country's democratic credentials to be a "sham".
Since the return of civilian rule in 1999, the ruling and dominant People's Democratic Party (PDP) has sought to rotate, or "zone" the office of president between the overwhelmingly Muslim north and the mainly Christian south.
Under this plan, the Mr Yar'Adua was supposed to be the northern president who would follow the two terms (1999-2007) served by the southerner Olusegun Obasanjo.
But fate dealt the plan a blow with Mr Yar'Adua's death from a long illness - and the subsequent accession to the presidency of another southerner, the former Vice-President Goodluck Jonathan.
The handover to President Jonathan was entirely peaceful, legal and constitutional.
But it has broken the deal planned by the godfathers of the powerful PDP. So some northern leaders are complaining that President Jonathan should not seek to stand as the PDP candidate in elections next year.
"The issue of power rotation is enshrined in the PDP's constitution," a leading northern politician, Atiku Abubakar, told me in his sumptuous, almost palatial Abuja home.
Mr Jonathan has not yet said if he will stand for the presidency next year
Referring to the deal within the PDP in the late 90s which saw Mr Obasanjo stand on the party's presidential ticket, Mr Abubakar said: "It was agreed that the presidency should be retained in the south" for eight years.
"And that when it reverts to the north it should also remain there for eight years. In fact there was a vote. I was there. And to the best of my knowledge that position has not been reviewed - so that is what it is today."
Mr Abubakar was coy about whether he intended himself to try to stand as the northern candidate next year - although most of Nigeria's well-informed newspapers seem to think he wants to.
But one thing to draw from his comments was clear; that a southerner such as President Jonathan should not, in Mr Abubakar's opinion, be the PDP candidate next year.
An unscientific poll of shoppers at the Wuse central market in the capital, Abuja, revealed anger about this politicking.
"We don't care where the president comes from," shouted one woman above the din of electricity generators installed in the market because of the failure of the state to provide adequate mains power.
"We don't care if he's from the north or the south - if only he would provide us enough power."
Many Nigerians say zoning has pandered to regional sentiments
"Zoning is not democratic. It's manipulative," said another young woman.
"What we want is the best person for the job - the most intelligent person. It's not about north or south."
'Blessing in disguise'
The concept of zoning the presidency - and a whole series of other top jobs - was presented by its architects as a way of ushering in political stability.
If the northern and southern politicians could agree to share posts, it was argued, it would spell an end to any excuses for further military rule.
In that sense the system has worked.
But many Nigerians say zoning has pandered to regional sentiments rather than picking the best man or woman for the job. They say the backroom deals between politicians in the PDP party are not democratic.
Nigeria is marking the passing of the late president with seven days of mourning
"The zoning system is nonsense as far as democracy is concerned," said political science lecturer Sadiq Abba in the rundown campus of the University of Abuja.
"I am a northerner but I don't see why Goodluck Jonathan shouldn't aim to stand for the presidency next year.
"The average Nigerian doesn't mind who his or her president is - their main concern is that they are being beaten black and blue economically. They simply want a government that will provide decent services."
Mr Abba said democracy in Nigeria was a "sham."
"May Allah bless Umaru's soul", the Muslim political scientist said.
"But his death may be a blessing in disguise for our democracy because for the first time it has exposed the mischief and the deception and the lies that have been taking place over the heads of the average Nigerian."