Nigeria's Muhammadu Buhari in profile
Former military ruler Muhammadu Buhari does not seem to know when to quit.
Defeated in the last two elections, first by President Olusegun Obasanjo in 2003 and then by President Umaru Yar'Adua in 2007, he has returned to contest Nigeria's highest office.
Mr Buhari is now facing defeat against the incumbent President Goodluck Jonathan, who is from Nigeria's southern Niger Delta region.
Mr Buhari had been hoping that dissatisfied members from the northern hierarchy of the ruling People's Democratic Party (PDP), would shift their loyalty to him.
Many members of the northern hierarchy feel it is "their turn" to hold the presidency, after President Yar'Adua, who is from the same northern state as Mr Buhari, died in office.
Although Mr Buhari is popular among the poor of the north (known as the "talakawa" in the north's Hausa language) mere popularity on the streets does not seem to have been enough.Suspicion
A Muslim from Daura in Katsina State, who has given his support to Sharia law in the north, Mr Buhari has previously had to deny allegations that he has a radical Islamist agenda.
This proved a problem for him in the 2003 polls; he failed to secure much support among Christians in the south, where he was viewed with some suspicion.
- Age 68
- Military ruler of Nigeria from 1984 to 1985
- Deposed in a coup
- Poor human rights record
- Seen as incorruptible
- Muslim from northern Nigeria
Mr Buhari mounted his assault on the presidency with the newly formed party, Congress for Progressive Change (CPC).
His former party, the All National Nigerian People's Party (ANPP) accepted the result of the 2007 elections, which angered Mr Buhari.
He resigned from the ANPP in 2009, following a lengthy court battle which upheld President Yar'Adua's victory.
The CPC is mounting serious challenges in elections to select governors in many states.
But it was unlikely that the opposition could mobilise enough support to win on a national scale.
Without an alliance with Nigeria's other opposition party, Action Congress of Nigeria, (ACN), a serious challenge to the presidency was doubtful.
Talks to form a "grand alliance" repeatedly failed, and the media in Nigeria all but wrote it off, citing disagreements between Mr Buhari and the ACN's leaders.
Mr Buhari has ruled Nigeria once, from January 1984 until August 1985.Neat queues
He took charge after a military coup in December 1983. It is a period remembered for human rights abuses and a fight against corruption.
The verdict on Mr Buhari's 20 months as Nigeria's leader is mixed.
About 500 politicians, officials and businessmen were jailed as part of a campaign against waste and corruption.
Some saw this as the heavy-handed repression of military rule.
But others remember it as a praiseworthy attempt to fight the endemic graft that prevented Nigeria's development.
He retains a rare reputation for honesty among Nigeria's politicians, both military and civilian, largely because of this campaign.
As part of his "War Against Indiscipline", he ordered Nigerians to form neat queues at bus stops, under the sharp eyes of whip-wielding soldiers.
Civil servants who were late for work were publicly humiliated by being forced to do "frog jumps".
End Quote Muhammadu Buhari, Oct 2005
If you choose correct leadership, there won't be any need for the military regime”
He also introduced a notorious decree to restrict press freedom, under which two journalists were jailed.
However, his attempts to re-balance public finances by curbing imports led to many job losses and the closure of businesses.
Prices rose while living standards fell, leading to a palace coup by Gen Ibrahim Babangida on 27 August 1985. Mr Buhari was imprisoned for 40 months.
Mr Babangida, who still retains an active role in Nigeria's politics wanted to speed up the restoration of civilian rule, which Mr Buhari did not see as a priority.
Mr Buhari has continued to defend his military coup of 31 December 1983.
"It is up to the people. If you choose correct leadership, there won't be any need for the military regime.
"The military came in when it was absolutely necessary and the elected people had failed the country," he said in October 2005.
When former President Olusegun Obasanjo was a military ruler in the 1970s, Mr Buhari held the key post of minister of petroleum affairs, but there is now little love lost between the former colleagues.
His coup ousted Nigeria's last civilian government, led by Alhaji Shehu Shagari, who won elections organised by Mr Obasanjo.
And this led to continuing questions about Mr Buhari's commitment to democracy.