I also doubt ChatGPT is just going to say “vote Republican”.

Propaganda is usually far more subtle than that. You can gently color the way the issues are framed, choose what to present as the important questions and deciding factors, omit to mention certain evidence or arguments, describe some candidates in appealing terms and others less appealingly, etc. All it needs to do is nudge some of the questioners a little to the right, not overtly or dramatically, but just enough to tip the votes statistically just a little bit towards the Republicans.