Nigeria is awash in nervous speculation over the health of President Muhammadu Buhari, who hasn’t appeared in public since he returned to the U.K. for medical treatment for an undisclosed ailment on May 7. Buhari, 74 and a Muslim, has formally designated his deputy, Yemi Osinbajo, acting president as he did when he was away on medical leave for 49 days from Jan. 20. The prospect of Osinbajo, a 60-year-old Christian, serving out the remaining two years of Buhari’s term raises the specter of sectarian tension in a country that has seen plenty of it in the past. Succession jitters also heighten concern about government paralysis at a time when the economy is in recession.

1. Why does the vice president’s religion matter?

Because Nigeria is divided between a mostly Muslim north and a predominantly Christian south, there’s been an unwritten agreement among the political elite since the end of military rule in 1999 that the presidency is rotated every two elections. So if Buhari dies or steps down and is succeeded by Osinbajo – as the constitution dictates – many in the north would probably feel shortchanged. They might insist that Osinbajo promise to step aside at the next elections in 2019 and allow his deputy – who would probably be a Muslim from the north -- to run instead.

2. Could someone other than the VP succeed Buhari?

Osinbajo has denied rumors that he’s under pressure from northern politicians to quit rather than be elevated to president. In such a scenario, Senate President Bukola Saraki, a Muslim, would take over, but only as a caretaker president until fresh elections are organised within three months. That would give the north a shot at winning the presidency.

3. Why is this north-south split so pronounced?

Northern Nigeria has a mainly agrarian economy and has long been poorer than the south, which contains the country’s oil wealth and the main commercial hub of Lagos. There are also linguistic and cultural differences. Sectarian tensions are usually worst in so-called middle-belt cities such as Jos and Kaduna, where more than 800 people were killed during riots that followed the 2011 election. In the northeast, Boko Haram’s campaign to impose its version of Islamic rule has killed ten of thousands since 2009. More recently, secessionists in the southeast have tried to revive the state of Biafra. Amnesty International said security forces have killed at least 150 of them in clashes.

4. How sick is Buhari?

It’s unclear. He was making short medical trips to the U.K. even before he took office. Only once did his office reveal a specific purpose: treatment of an ear infection in mid-2016. Otherwise, his spokesmen said that his trips were for tests and that he’s “hale and hearty.” While Buhari appeared in photographs with visitors during his stay in London earlier in the year, and spoke with U.S. President Donald Trump on the phone on Feb. 13, there have been no images of him this time around. His aides released an audio message said to be from him during the Muslim Eid holiday, the only time people heard directly from him so far. The lack of full disclosure about his status has spawned speculation in Nigeria that he’s dying.

5. How long can Buhari be away?

The president is entitled to 60 days of annual leave, according to the constitution. By law he can be removed for medical reasons if his Cabinet concludes that he’s become incapacitated, an unlikely act from loyalists, according to Clement Nwankwo, an Abuja-based constitutional lawyer. Only the national legislature has the power to unseat Buhari. For that to happen, two-thirds of lawmakers and the ruling party must support the move.

6. What challenges would a successor face?

His successor would face the tough task of reviving an economy that shrank for the first time in a quarter century last year and diversifying it from oil, which accounts for almost all exports, as well dealing with resurgent ethnic tensions in the wake of demands for secession as Biafra in the southeast. They would also need to win back the trust of foreign investors, who fled in the past two years as Buhari and the central bank opted to peg the naira instead of letting it drop along with crude prices, as other producers such as Russia and Kazakhstan did with their currencies. Other problems include corruption, which is still rife, and bureaucracy, both of which businesses say stifle their operations.

•Text courtesy of Bloomberg.

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