The Man is the story of the first black president of the U.S.
Written by Irving Wallace in 1964, before the 25th Amendment and filmed in 1972, the plot is, basically:
The president and the speaker of the house are killed in West Germany when its parliament buildings suffer a collapse. The vice-president, elderly and in in very ill health, refuses to assume the office, pointing out that they'll need another replacement almost immediately.
Arthur Eaton (William Windom), the Secretary of State, is urged to take the office, but he points out that the law on the line of succession places the job with the President Pro Tempore of the Senate, Douglass Dilman (Jones).
Obama's rise has been quite different and there was no assassination in The Man, so perhaps that's why the novel has been largely ignored.