ABUJA, Nigeria — The calls for him to quit were already loud, coming from two former presidents, a prominent pastor and newspaper editorials. Even Catholic bishops weighed in with criticism.

Now, the president of Nigeria is facing a new crisis: the mass kidnapping of 110 girls from their school late last month, prompting another wave of outrage at the government.

The pressure is mounting on President Muhammadu Buhari to step down after his first term expires next year. A diverse range of Nigerians have joined the chorus, and while the presidential vote is still almost a year away, campaign season in Nigeria is in full swing. Billboards have popped up in parts of the country and election news dominates the headlines.

Nigeria’s Constitution allows Mr. Buhari to seek a second term, but already his opponents and former allies are piling on. Even his wife has emerged as a detractor of sorts, using social media to post video clips of politicians criticizing her husband’s presidency.