The 79-year-old Biya has removed term limits from the constitution and vows to seek re-election in 2018 if his health permits. Official results showed he won last year's election with 78 percent of the vote.
The opposition, though, accuses Biya of commanding extensive control over the parliament, judiciary and the army. They say ruling party officials prevented the opposition from holding an anti-Biya rally Tuesday. And they point to the fact that nearly two-thirds of Cameroonians lack access to potable water and electricity.
Observers also warn the country may plunge into a protracted power scramble in the event of Biya's abrupt demise.