Trump needs to keep the Rat nominee boxed in, on the Left, and not allow them to move towards the center.
He needs to note everything they are saying, and use those words against them, so they would either have to disavow those words, or keep to the Left.
He can say whatever he wants, what will matter is what he signs.
If he signs universal background checks (registration), magazine restrictions, scary black gun ban and red flag he will lose.