(Nigerian president Goodluck Jonathan speaks at the launch of his presidential campaign in the central city of Lafia, Nassarawa state February 7, 2011/Afolabi Sotunde)

From Islamic police enforcing a ban on beer and prostitution to its centuries-old market and mosques, Nigeria’s northern city of Kano feels like a different country to the pulsating southern sprawl of Lagos. Its low-rise buildings and dusty tree-lined streets have more in common with the sleepy Sahelian cities of Niger or Chad than with Nigeria’s commercial hub, a city built on hustle and home to some of Africa’s largest companies and richest tycoons.

Securing support in this ancient city — the second most populous after Lagos — and other parts of Nigeria’s Muslim north will be key if President Goodluck Jonathan, a southerner, is to clinch victory in the first round of elections next month.

As the incumbent, Jonathan is considered the front-runner, but his main rival, Muslim ex-military ruler Muhammadu Buhari, has strong grass roots support in the north and the opposition is hoping to force a run-off.

“What we are looking for is change. The only option is Buhari,” said Sagir Haruna, a textile merchant in Kano’s Kwari market, a labyrinth of narrow alleyways packed with stalls made of wooden lattice and corrugated iron roofs. Cheers of “Buhari, Buhari” rang out from other stall holders as sirens wailed in the streets outside, signalling a security build-up ahead of Jonathan’s arrival in the city, the latest stage of a campaign which has focused on the north this week.