The bishops also addressed the media, calling them a "very crucial actor" in the electoral process, and encouraging the media to show continued professionalism and commitment to fulfilling its duties.
Kenya's President Uhuru Kenyatta is seeking re-election.
In his 2013 race for the presidency, he and his deputy William Ruto had been indicted by the International Criminal Court on charges of crimes against humanity. His campaign prompted warnings from the U.S. and U.K. governments if he were elected, BBC News reports.
However, the warnings did not have much consequence. He mobilized many African leaders to pressure the international court. Both cases were dropped due to a lack of evidence, with the International Criminal Court saying prosecution witnesses were intimidated and the cases could resume.
Kenyatta, the son of Kenya's first president, has portrayed his 72-year-old opponent Raila Odinga as an agent of foreign governments who works to serve former colonial powers. He has also portrayed Odinga as an "analog generation" of politicians who must make way for the younger "digital generation." His family owns a TV channel, a newspaper, and a number of radio stations, among many other business interests.
Odinga, a son of Kenya's first vice-president, is making his fourth bid for the presidency. He has had different policies alliances in his career and is now running under the National Super Alliance, a coalition of Kenya's main opposition groups. He aims to win drawing from his ethnic community, the Luo, as well as the Luhya, Kalenjin and Kamba groups.
Odinga studied to be a mechanical engineer in former East Germany, and was MP for Africa's biggest slum, Kibera. He was imprisoned for attempting to stage a coup in 1982 against a one-party dictatorship. Though he initially denied the claim, he admitted his central role in a 2006 book. He was imprisoned from 1982-1988 and 1989-1991.
He has promised to serve only one term in office and has convinced many potential rivals to back his candidacy instead.