The fifth amendment blocks prosecuting people multiple times for the same crime, so state and federal laws are limited to their own jurisdictions. If they're in state jurisdiction, the state law applies and federal does not. Federal jurisdiction is limited to edge cases like Washington DC, national parks, coastal waters, etc. or crimes that involve crossing state lines.
Both the Federal and State governments have jurisdiction. If the either the state or federal charges get pardoned or acquitted, the other can also prosecute, double jeopardy rules don't affect dual sovereignty.
Edit: The funny thing about this dual soreignty, is that he can get a Jury Nullification on state charges, but then get charged with federal charges and get a different Jury, and this Jury might decide to not nullify and he can still get convicted.
Or we convince him that it will improve his approval ratings for the election in November, and hope he truly DOES have dementia. Maybe he won't realize it's December? Maybe he forgot he's not running for a 2nd term?