Tonight’s special TCM movie theme, based on tomorrow’s start of the Republican National Convention, is titled “Conventional Wisdom,” and it begins with two movies that use political conventions as a backdrop. First up is this 1964 movie, with a screenplay written by Gore Vidal, about the two leading candidates for president of one party. Both have secrets, and those secrets are known, and perhaps will be put in play, by their rival camps. Henry Fonda and Cliff Robertson (pictured) play the dueling candidates at the convention. After that film, at 10 p.m. ET, comes 1969’s Medium Cool, starring Robert Forster, playing a TV cameraman covering the volatile 1968 Democratic National Convention. If you want a frightening peek at what some people are afraid may occur in Cleveland this week, watch Medium Cool.