Let me suggest a different direction.
The risk is that a niche candidate will make the idea too associated with them, which will let everyone else off the hook -- it's easy to dismiss a weirdo talking about weird stuff.
A better direction might be to find a second tier candidate that wants to differentiate themselves, and help them with good snappy talking points that sound good in a debate. I think that's both higher impact and has a much smaller chance of pushing things in the wrong direction accidentally.
Andrew Yang. He signed the FLI letter, transformative AI was a core plank of his run in 2020, and he made serious runs for president and NYC mayor.
In the modern climate regulation makes everything worse. It is guaranteed to make AI x-risk worse. Probably not in obviously predictable ways, but it will, no exceptions. Read recent posts by Zvi and Scott Alexander. Every problem people tried to solve with regulation got worse because of it. Just... don't involve bureaucracy, or Roko's Basilisk will force you to submit 100-page forms over and over again for eternity, rejecting each one on a technicality. Ronald Reagan said that "we are from the government and we are here to help" are the nine most terrifying words in the English language, and, being President, he knew what he was talking about. It has only gotten worse nearly 40 years later.
With AI risk getting significant media attention lately (FLI open letter, Eliezer's letter), I think it's plausible that the Overton window has expanded enough where a presidential candidate talking about it won't get immediately laughed off stage.
In addition, there seems to be increased positive sentiment around a global treaty to pause AI development within the rationalist/EA community.
It seems reasonable to me then that the rationalist/EA community should try to put forth a candidate for the US 2024 presidential election where one of their main platforms is mitigating existential AI risk.
I wouldn't expect them to succeed, but hopefully they can at least open the Overton window further to the point where at least other candidates engage with it a little and voters ask some questions.
Has there been any planning/thinking around this?