A Nigerian minister has promised to quit if President
Women's affairs minister Aisha Alhassan said she would back former vice-president Atiku Abubakar for the presidency at the next election in 2019 rather than the incumbent.
"If today Buhari decides to go for re-election... I will go and kneel before him and tell him, 'Father, I'm grateful for the opportunity you have given me to serve in your cabinet but you know Atiku is my mentor, staying around you will portray me as a hypocrite and I'm not one', that is if Atiku declares his interest to contest," she told BBC Hausa radio.
Speculation has been rife in Nigeria about whether Buhari, 74, will stand again, after he has spent much of the year in a London hospital with an undisclosed illness.
The government maintains he is back at work, although he has kept a low profile since returning from the British capital last month.
Buhari has skipped and cancelled weekly cabinet meetings, chairing his first gathering of senior ministers in five months last week.
Alhassan disclosed her allegiance on Wednesday after being asked whether Buhari had told anyone he planned to run in 2019.
She said: "In 2015 prior to the election, when Buhari decided to contest following intense pressure, he declared that he was going to serve one tenure, that is four years.
"And to date no-one can claim Buhari has expressed any desire to stand for re-election in 2019."
Buhari made Alhassan women's minister after she narrowly failed to be elected to run the eastern state of Taraba, making her the country's first female state governor.
Abubakar, whom Buhari beat to be the All Progressives Congress (APC) party's presidential candidate for 2015, nominated her for the ministerial post.
The former customs service chief, 70, who served as vice-president under former president Olusegun Obasanjo in the 2000s, is widely tipped to try again for the top job.
He has been touring the nation to drum up support but senior APC figures maintain Buhari remains the candidate to beat, should he decide to contest.
Alhassan made no further comment when asked about her remarks by AFP.
Nigerian politics is largely dependent on patronage, with little to separate the main parties other than personalities.
In 2015, the Peoples Democratic Party haemorrhaged support because ex-president Goodluck Jonathan allegedly reneged on an apparent pledge to serve just one term.
A slew of lawmakers switched to Buhari's APC, ensuring the first opposition win in Nigeria's history.