Former Nigerian military ruler Ibrahim Babangida has withdrawn from the race to be the ruling party's presidential candidate in next year's elections.
Mr Babangida ruled Nigeria for eight years
Mr Babangida was seen as one of the frontrunners for the April polls but his campaign is likely to be weaker without the ruling party's support.
An aide said Mr Babangida had pulled out because President Olusegun Obasanjo said he would support a rival bid.
Political tension is high in Nigeria, with Mr Obasanjo standing down.
The announcement comes as the ruling People's Democratic Party starts choosing from a shortlist of about 30 people to become its candidate.
Mr Babangida, known in Nigeria as IBB, ruled for eight years until he was forced from power by popular protests in 1993 after he annulled elections that were described as the country's freest and fairest yet.
The BBC's Mannir Dan Ali in the capital, Abuja, says it is not clear whether Mr Babangida will become a candidate for another party, or back his close associate and former spy chief General Mohammed Aliyu Gusau for the PDP ticket.
"You never know what IBB is going to do next. That's why we call him Maradona," said Pini Jason, a leading political columnist for the Vanguard newspaper, referring to Argentine former football star Diego Maradona.
But he believes Mr Babangida is still likely to contest the polls.
"I'm sure he's going to pick up the ticket of another party. He owns three or four parties," he said.
Huge adverts with slogans like "IBB - experience Nigerians need" started appearing a year ago, reports the Reuters news agency.
Mr Babangida's aide, retired Colonel Habibu Shuaibu, told the BBC that Mr Obasanjo's backing for Katsina State Governor Umar Yaradua showed there was no level playing field in the PDP contest.
But PDP deputy national chairman Bode George insisted that the party did not have an anointed candidate.
Last week, Vice-President Atiku Abubakar withdrew from the PDP race.
He is expected to run on behalf of a rival party.