There are well-attested examples of the use of nicknames for popular political figures going all the way back to Athens and Rome.
Examples of this would be Pericles, who was nicknamed "Squill-head" (he apparently had a very large and bulbous head - think "Egg-head" in our usage) and Caligula ("Little Boots"). Other Athenian political nicknames included Bleary Eyes, Smoky, Hempy, and Quail. The Roman cognomen often started as a nickname, but then stuck so well that it became hereditary.
Often you have the combination of the use of the nickname to refer to the figure in the third person in conversations, along with its use in the chants of crowds, versus the use of terms of formal address when speaking to the politician in person. But that happens in the modern era also - he's Joe Biden when you're talking about him online, but "Mister Vice President" if you have the opportunity to talk to him in person.