ie, Trump is actually a rapist. Fully meant the "grab them by the pussy" thing. He walks the monster walk (or did, before infirmity got him) Vance doesn't have the spine to rape anybody... Which is good! Unless you're trying to be the heir apparent to the Rape Party for Rapists
Trump gives his "that's a nice country, be a shame if anything happened to it" stuff and people know there is a nonzero chance he launches nukes just because he feels like it and it would make him laugh. Nobody thinks Vance would pull the trigger.
Again, these are all good things in the grand scheme of things! But it's also why the party won't rally around Vance as it will coagulate, scab, and then peel away.