It is the conflict that gets conveniently buried, by the African Union, by its neighbour Nigeria and by the UN. Yet the deepening rebellion in western Cameroon against President Paul Biya's regime could explode his bid, announced last week, for a seventh term, and trigger regional mayhem. Since the rebellion started two years ago, more than 200 have been killed and over 100,000 driven from their homes.

National opposition could focus foreign attention on the Biya government's appalling record on economic management and corruption, and now a growing sense of the country's break-up. With a co-ordinated and well-funded alliance, impressive opposition figures such as economist Antoine Ntsimi and lawyers Akere Muna and Maurice Kamto could challenge Biya's rule. But there is no sign that Biya would allow free elections. The last time that happened, in 1992, he lost to Anglophone leader John Fru-Ndi.

While the Cameroonian army is helping Nigeria fight the Boko Haram insurgents, President Muhammadu Buhari is unlikely to pressure Biya on the  crisis. Indeed, rights activists accuse Nigeria of collusion. But Cameroon's economy is stalling and Biya is struggling to pay soldiers and civil servants. That could mean ending military cooperation with Nigeria on the northern borders or opening negotiations with the rebels. Both options are risky but doing nothing – Biya's default mode – could bring his 35 years in power to a dramatic finale.