Are you familiar with dog whistles?
Which is basically projecting one's bias in the belief that any reference to others is somehow code for a racist attack. Seriously folks, there is not even a hint of race baiting in that. Here in Virginia we recently had some cases of fraudulent voter registrations. If my local GOP informs me, as a voting Republican, to watch and make sure no funny business goes on at my local polling booth, is that a racist attack? If the answer is no, then there is nothing wrong with what Trump is saying.