A lot of circumstantial evidence of political maneuverings to get the Manchurian ( Muslim) candidate into office.
This "game" is never straight and simple - that's exactly why the author is so careful to introduce the facts and the quotes from the "players" themselves.
"... [He] is the kindest, bravest, warmest, most wonderful human being I've ever known ..." - from Manchurian Candidate (1962)
"Our worst enemies here are not the ignorant and simple... our worst enemies are the intelligent and corrupt" - Henry Graham Greene