What’s the probability that there’ll be at least 1 primary debate including the frontrunner?

[Mr. Morden]

Presumably, if Biden runs for reelection, he’ll have no serious primary challengers.  (For that matter, there’s also an outside chance that if Harris is running instead of Biden, she’ll also have little opposition, and wouldn’t be running against anyone she deems worth debating, though that’s more of a stretch.)

If Trump runs for the GOP nomimation, he’d also at least start out with a big lead in the polls for the nomination.  It’s not clear how many prospective challengers would run against him, but even so, if prospective challengers hold a debate and invite Trump to it, it’s not clear he’d bother to show.

So the question is, what is the probability that, in at least one of the two major parties, we see at least one presidential primary debate in the 2024 cycle **in which the frontrunner for that party’s nomination at that point in time actually participates**?  If it doesn't happen, this would be the first time in decades that it doesn't.

Let's say “frontrunner” = Amongst candidates officially in the race at that moment time, whichever one has the best poll #s.  By this definition, I guess it's at least possible that Trump might take so long in deciding whether to run or not that other GOP candidates get into the race while he's on the sidelines, and have a debate amongst themselves.  For these purposes then, that debate would count, since Trump wouldn't have been in the race at that point in time.

[Skill and Chance]

Trump would never agree to Republican debates as long as he's leading in the polls.

Biden wouldn't agree to Democratic debates, but Harris likely would.