The Candidate was released a month prior to the 1972 California Presidential primary. Promotional sheets were put up in southern California resembling political posters. They had simply a photo of Robert Redford, with the slogan, "McKay: The Better Way!" - "McKay" got write-in votes in the June election.
Robert Redford and Michael Ritchie had recently worked together on Downhill Racer (1969), when they approached Jeremy Larner together wanting to make a movie about "a candidate who sold his soul." According to Larner: "Warners would not have financed the film were not Redford willing to take responsibility for it, and though he did not want the credit, he was a most conscientious producer from beginning to end, and the movie certainly reflects his personality."
"The Candidate" was one of a handful of 1972 Warner Bros. releases to feature a rare, short-lived version of the WB shield logo, with a solid blue background and "A Warner Communications Company" tagline (WCI had just become Warners' parent company, but the familiar '70s era Saul Bass logo had not yet been designed). "Deliverance" was the only other high-profile WB movie to use this logo.
The trivia item below may give away important plot points.
Photographer Stanley Tretick, best known for his iconic photos of John F. Kennedy with his children in the Oval Office, appears in the chaotic scenes as McKay reaches his victory, as part of the throng crushing around him. Tretick shot promotional stills for this and other Robert Redford films.