All of the talk of the possibility of brokered party conventions made me think of the movie "The Best Man" (1964), starring Henry Fonda and Cliff Robertson.
Even though it's fiction, it's a fascinating look back at the day when political conventions actually decided the party's nominee. In the past few decades, of course, the nominee has already been decided long before the convention arrives.
The plot of the movie is that Fonda's character, William Russell, an idealistic, high-minded presidential candidate, is in a tight race with Robertson's character Joe Cantwell, a down-and-dirty politician, as their party convention begins.
The party is never named, and this movie is more about the behind-the-scenes political machinations than any actual issues. Some critics have compared Fonda's character to Adlai Stevenson and Robertson's character to Richard Nixon, who obviously wouldn't have been at the same party convention in real life. UPDATE: After I first posted this, I saw that screenwriter Gore Vidal himself made this comparison.
The candidates are trying to line up support from the delegates, and they're also competing for the blessing of a plain-spoken, Harry Truman-like ex-president, Joe Hockstader (played by Lee Tracy), who is their party's elder statesman.
Robertson threatens to expose a secret from Fonda's past, and Fonda must decide whether to retaliate in kind, something that runs counter to his nature.
The movie's screenplay is by Gore Vidal.
It's an interesting movie -- some of it is hyped-up soap opera, of course, but it also raises questions about the balance between the idealism and pragmatism required to do the most difficult job in the world.
If the movie pops up on TCM this election season, and I suspect it will, it's well worth a watch.
ANOTHER UPDATE: IMDb says that actor Ronald Reagan was considered for a part in the movie, but studio executives rejected him because they didn't think he looked presidential enough!