Nigeria relatively little violence or voter fraud, in contrast to previous elections. In the March 2015 election, Muhammadu Buhari defeated Goodluck Jonathan by roughly 2 million votes. Observers generally praised the election as being fair. Jonathan was generally praised for conceding defeat and limiting the risk of unrest. Nigeria is a federal republic modelled after the United States, with executive power exercised by the President. It is influenced by the Westminster System model in the composition and management of the upper and lower houses of the bicameral legislature. The president presides as both head of state and head of the federal
President of Nigeria group of northern army officers revolted against the government, killed General Johnson Aguiyi-Ironsi, and appointed the army chief of staff, General Yakubu Gowon as the head of the new military government. In 1975, General Yakubu Gowon was deposed and General Murtala Mohammed was the Head of the Federal Military Government of Nigeria until his assassination in 1976. In 1976, General Olusegun Obasanjo was made head of state in a meeting of the Supreme Military Council, keeping the chain of command established by Murtala Muhammed in place. In 1979, Nigeria adopted a federal presidential constitution, with provision for an executive President