Goodluck Jonathan was sworn in Thursday as the president of Nigeria, Africa's most populous nation, just hours after the death of the oil-rich country's elected leader whose long illness had sparked a leadership crisis, according to AP. Jonathan put on a sash bearing the green, yellow and white colors of Nigeria just after 9 a.m. (0800 GMT), signifying he had formally taken over for President Umaru Yar'Adua. Yar'Adua, who long had suffered from kidney ailments and was recently hospitalized in Saudi Arabia because of heart inflammation, died at 9 p.m. Wednesday after apparently succumbing to his ill health. Yar'Adua's death came almost three months after Jonathan had assumed control of Nigeria as acting president and less than a year away from the next presidential elections in a country once plagued by military coups. Jonathan now will serve as president through next year's vote, likely to be held by April 2011. He also will be able to select a vice president to serve underneath him, subject to Senate approval. In a brief address, Jonathan promised that his administration would focus on good governance during its short tenure, focusing especially on electoral reform and the fight against corruption. «One of the true tests will be that all votes count and are counted in our upcoming presidential election,» Jonathan said. An unwritten power-sharing agreement within Nigeria's ruling party calls for the presidency to alternate between Nigeria's Christians and Muslims. Yar'Adua, a Muslim, was still in his first four-year term though. Jonathan also said Thursday that peace in the Niger Delta, home to the country's oil industry, remains a priority. Attacks by militants there last year crippled oil production. Yar'Adua had tried to peacefully end the insurgency but those efforts frayed due to his increasing illness. Jonathan said Yar'Adua left a «profound legacy» for him to follow. «He was not just a boss, but a good friend and a brother,» Jonathan said. Jonathan, a quiet marine biologist fond of bowler hats, wore the traditional black clothes of the Niger Delta region to his inauguration. He remained seated during Muslim prayers offered on Yar'Adua's behalf, but stood for a Christian invocation. Yar'Adua is to be buried before sundown Thursday in his home state of Katsina. He had gone to a Saudi Arabian hospital on Nov. 24 to receive treatment for what officials described as a severe case of pericarditis, an inflammation of the sac surrounding the heart. He failed to formally transfer his powers to Jonathan, sparking a constitutional crisis in Nigeria, home to 150 million people. Jonathan assumed the presidency Feb. 9 after a vote by the National Assembly while Yar'Adua was still in Saudi Arabia. Lawmakers left open the possibility for Yar'Adua to regain power if he returned to the country in good health. He returned on Feb. 24 but never reappeared in public and did not assume power again.