DAKAR, Senegal — Nigeria’s ailing president, Muhammadu Buhari, had been seen in public so rarely that some Nigerians were convinced he was dead. Some of his supporters have called on him to step down, at least until his health improves.
His wife recently defended him, posting on Twitter that the president’s condition was “not as bad as it’s being perceived.”
As the worries grew, Mr. Buhari desperately needed a victory to show that he was still in control, securely at the helm. Over the weekend he got one: Dozens of the nearly 300 schoolgirls kidnapped three years ago by Boko Haram were released, by far the biggest break in a case that shocked the nation and the world.
But Mr. Buhari, 74, barely reveled in the achievement. He met with the girls briefly Sunday, then flew back to London, where he has spent nearly two months this year on medical leave.
The nature of the president’s illness is still a mystery, constantly played down by advisers who have called him “hale and hearty.” But his prolonged public absences have prompted anxiety in a country that is trying to dig out of
recession while fighting a brutal war against Boko Haram, the Islamist militant group.
“I’d like to assure all Nigerians there is no cause for worry,” Mr. Buhari said Sunday on Twitter.
Among the well-wishing from those responding on Twitter were expressions of fears about a rudderless country.
“Just resign,” read one post.
The release last weekend of 82 of the schoolgirls kidnapped from the village of Chibok consumed and elated people around the world. But in Nigeria the news was quickly caught up in another drama: Who, exactly, is in charge of Africa’s biggest economy?
Officially, Vice President Yemi Osinbajo has taken over while the president is in London. But some Nigerians are asking how Mr. Buhari can run the country when he has been too ill to attend his own cabinet meetings.
“There is today no clear leadership,” said Sylvester Odion Akhaine, an associate professor of political science at Lagos State University. “His absence harbors potential seeds of instability.”
Some critics even contend that the timing of the girls’ release was suspicious, intended to distract the nation from the president’s latest medical trip to London.
Ayodele Fayose, the governor of Ekiti State, issued a statement saying it had become commonplace for Mr. Buhari to “resort to flying dubious kites and selling cheap dummies to distract the people and obfuscate the issue at hand.”
The questions over the president’s fitness to rule come at a time when Nigeria is reeling from low oil prices and a humanitarian crisis caused by Boko Haram in the northeast, where some people are on the brink of famine .
The troubles do not end there: Angry residents of the oil-rich south, where many feel cheated out of their share in the nation’s oil wealth, are blowing up pipelines.
Given all the uncertainty, various groups have called on Mr. Buhari to resign or take a lengthy medical leave of absence until it is clear he is well enough to lead. Femi Adesina, a special adviser to Mr. Buhari, rejected those calls.
“Over 15 million people voted the president into office,” he said. “If between 15 and 20 people are asking for resignation, their will cannot override the will of millions of others. Millions of Nigerians are praying for, and wishing the president well.”
Nigerians fear a rerun of 2009, when the president, Umaru Musa Yar’Adua, was ill for months, traveled to Saudi Arabia for treatment and never handed over power. Parliament eventually appointed his deputy, Goodluck Jonathan, to take over, and Mr. Yar’Adua died in the presidential villa.
Mr. Jonathan served out the term and was later elected to office, presiding over a corruption-plagued administration until he was ousted by Mr. Buhari in the last election.
Many Nigerians blame Mr. Jonathan for failing to try to rescue the girls abducted from Chibok immediately after militants stormed their boarding school during exam week in 2014. Even with the dozens released over the weekend, more than 100 of the girls remain unaccounted for, many of them believed to be still in Boko Haram’s clutches.
Mr. Buhari came into office in 2015 with two major promises: ending rampant corruption and defeating Boko Haram. He has made progress toward both goals.
His administration has uncovered suspicious stacks of cash — millions of dollars’ worth — in the home of a former national oil executive. It has charged a former national security adviser with stealing many more millions of dollars that were supposed to be used to buy weapons to fight Boko Haram.
Under Mr. Buhari, a former general, soldiers have made major gains against Boko Haram, storming forest hide-outs and scattering fighters into the countryside. The group no longer holds large swaths of territory in Nigeria but still stages regular suicide attacks and strikes on military convoys and outposts.
Mr. Buhari had also pledged to clean up the human rights violations of the military, but soldiers are still accused of killing civilians.
The release of the girls from Chibok resulted from months of negotiations by his administration with militants, beginning six months ago after a smaller group of 21 girls
was released . In the end, Mr. Buhari endorsed handing over as many as six Boko Haram suspects who Western diplomats have said were high-ranking commanders.
Some Nigerians are worried that Mr. Buhari has ceded leadership to what is often referred to as his “cabal,” a group of close advisers who they fear are making political appointments and important decisions for an incapacitated president.
Bisi Akande, a former national chairman of Mr. Buhari’s political party, said he worried that this inner circle already was “attempting to feast on the health of Mr. President in a dangerous manner.”
“In the end, it could drag the entire country into avoidable doom,” he said.
Last week, a prominent human rights lawyer called for the suspension of bank activity, Parliament and all official business until Mr. Buhari gave up power.
“I hereby call upon all the good people of Nigeria across the land to rise up to challenge the cabal that is holding Nigeria to ransom in the face of the apparent incapacity of the president to direct the affairs of Nigeria,” the lawyer, Ebun Adegboruwa, said in a statement.
Nigeria’s Constitution calls for a president to be fit and in charge, and lawmakers could have doctors examine Mr. Buhari. Some opponents have sought that, but it seems unlikely lawmakers will resort to such measures.
During both his medical trips to London, Mr. Buhari has officially ceded power to the vice president, Mr. Osinbajo. Mr. Osinbajo, a former partner at a law firm who belongs to Mr. Buhari’s party, has been praised during his stints as interim president.
Mr. Osinbajo traveled to the Niger Delta in the south of the country to meet with leaders upset about economic inequalities — a trip Mr. Buhari had scheduled last year but canceled after oil pipeline attacks. He has led cabinet meetings, helped shepherd legislation, and on Monday presided over a major business forum. He even weighed in on a national obsession: arguing over which country has the best jollof rice.
His performance has put to rest fears of turmoil in a nation that has suffered through coups, military rule and a bloody separatist movement in the south. But positioning is well underway for who would serve as Mr. Buhari’s replacement on the 2019 presidential ticket for his party, the All Progressives Congress.
The jockeying takes into account a principle that has been in place since the 1999 end of military rule: the informal agreement that the presidency rotate after every two terms between the overwhelmingly Muslim north and Christian south.
Mr. Buhari is from the north, and if he leaves office before his term is finished, Mr. Osinbajo, a southerner, would take over until the term ends in 2019. But some in their party might argue for a northerner on the ticket for the next election because the north’s stint would be cut short.
Mr. Buhari’s supporters are brushing off talk of his successor. They say the president is fully capable of doing his job.
Bola Tinubu, an All Progressives party leader and the former governor of Lagos State, released a statement this week calling for Nigerians to stop speculating about the health of their president and focus on his achievements.
“His policies have begun to bear fruit,” he said. “Given the complex menu of problems he has faced, President Buhari has done well in a tough situation.”
Dionne Searcey reported from Dakar, and Tony Iyare from Lagos, Nigeria.