Nigeria's president Muhammadu Buhari on Monday handed responsibility for his re-election campaign to Bola Ahmed Tinubu, a sign of rapprochement with the man who masterminded his landmark 2015 election win.Former Lagos state governor Tinubu, head of the All Progressives Congress (APC), helped Buhari become the first opposition candidate to defeat a sitting president in Nigeria.But the pair reportedly fell out after Tinubu was sidelined once he had helped swing support in the populous and more prosperous southwest.Nigerians go to the polls to elect a new president and parliament on February 16, with governorship and state assembly polls scheduled for two weeks later.Buhari, 76, wants a second, four-year term of office. The former military ruler is under pressure for his record on security, the economy and tackling corruption, as well as questions about his own health.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook. He has acknowledged that the campaign will be tough. But on Monday he told senior party members that while he would be "deeply involved", he would not let campaigning get in the way of governing. "Asiwaju Bola Ahmed Tinubu, my co-chairman, will be fully in charge," he said. Buhari and Tinubu chair the APC Presidential Campaign Council.Tinubu, 66, has long been rumoured to have presidential ambitions.His chance might come in the 2023 elections, when the presidency nominally rotates to the south after eight years of a northern incumbent.Buhari's main opponent next month is former vice-president Atiku Abubakar, from the main opposition Peoples Democratic Party (PDP).