A joint US observer team on Wednesday called on Nigeria to ensure that the forthcoming elections are peaceful, credible and transparent.Nigerians will go to the polls in February to elect a president and federal parliament. Governor and state houses of assembly votes will take place two weeks later. A delegation of the International Republican Institute (IRI) and National Democratic Institute (NDI), led by former US assistant secretary for African affairs Linda Thomas-Greenfield, have been visiting Nigeria this week."The 2019 general elections could be another important step in consolidating Nigeria's democratic development," said Thomas-Greenfield. The delegation said positive efforts were being made to conduct more transparent, and inclusive elections, but confidence in the process and the outcome of the elections could still be undermined.The IRI and NDI said they would send foreign observers for the crucial votes.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook. President Muhammadu Buhari, of the All Progressives Congress (APC), who came to power in 2015 and is seeking a second term in office, has promised a credible election.Buhari, 76, faces a formidable challenge from an array of opposition candidates, including former vice president Atiku Abubakar of the Peoples Democratic Party(PDP). Security on polling day is a recurrent concern in Nigeria, which has a history of violence stoked by politics, ethnicity and religion.In 2011, some 1 000 people were killed after clashes between supporters of Buhari after his defeat to Goodluck Jonathan. He won the 2015 poll against Jonathan who immediately conceded defeat.Last week, Buhari and other candidates signed a peace deal ahead of the February 16 vote.