"Heels-up Harris" is my favorite but it would shock me if he said it (wouldn't be the first time).
This one's complicated. He can't point out that she's the real candidate because a) that doesn't translate well into a nick-name: "President Harris?" --yikes! b) he can't reference her slave owning ancestral history: "Kunta Kinte Kamala?" --noppity, nope, nope. c) he can't attack her on her excessive prosecutorial actions: "Hound Dog Harris?" -- he's pro cop.
So he's attacked her as being far, far Left. Which we grok but not so sure the rest of America does. Anyway, so taking that approach: "Komrade Kamala?"
What are others?
:Kumala", Trump started mispronouncing her name after they called it "racist and sexist" to. Also she isn't even "far left", just anti American people plus pro swamp and growing her power. Just like Biden nowadays, but she is worse at it. Biden gave us an important clip when he said "Anyone who questions him were "Republicans want to focus on me when they worship Trump anyways and we need to focus on how bad Trump is". Kamala is that but worse if she did a public appearance, and Trump's main personal attacks need to come around to how "they don't respect the American people"