I can see Trump issuing an emergency executive order on the eve of mid term voting commanding all of ICE, Homeland, FBI, and anyone else available under his wing being assigned to poll stations throughout the US to monitor elections, if not directly check i.d.'s and verify citizenship. Paddy wagons parked outside. Any local officials who get in the way (interfere) with Federals doing their job are arrested on the spot. No doubt demonstrators appear and tear gas flows freely.
Maybe he even declares "martial law" for 48 hours "to insure fair elections" so that liberal leaning courts are shut out, injunctions are ignored. Who would enforce an injunction in any case ? Certainly not the Feds under Trump.