He did not call him opponent a "monkey".
Correct. He did not call his opponent a 'monkey'. What he said by implication was that his opponent's policies would "monkey up" the state of the state, OR that a vote for him would "monkey up" the election itself, depending on what "this" refers to.
And to do that means "to apply a monkey to" .... whatever "this" is. Just as "to box this up" would mean "to apply a box to this" or "to polish this up" would mean "to apply polish to this".
Just as:
"To louse up" = "to apply lice to..."
"To butter up" = "to apply 'butter' (smarmy ingratiation) to..."
"To flesh out" = "to apply more substance (flesh) to...".
"To gum up" = "to apply gum to..."
So you are once again correct, he did not call his opponent a monkey directly. What he did indirectly was to describe who the actor would be in a potential scenario -- a monkey.
Strictly speaking, if "this" refers to the election he could be speaking of the voters. As in "we can't have too many monkeys voting". And you can choose for yourself what that might mean. Maybe.
All sorts of possibilities. Again, only he knows within his head what he had in mind. But clearly he chose the term deliberately. Let's agree that, if his purpose was to fling a racial slur, then this is how it would be done with plausible deniability --- indirectly.
You are almost there. (bolding added)
What he did was, with a metaphor, was describe the ACTION, not the actor.
This coming Sunday, I plan to pig out, at a steakhouse buffet.
DId i just describe myself, or my action?