We need to dispel this notion that there are Federal elections. That animal does not exist except in one instance: state electors voting for POTUS. Outside of that every election is a STATE election. Federal means nationwide, across state lines. The voters of Illinois don't cast votes for US Senator from the state of Iowa, etc. If there were Federal elections then D.C. would have its own voter registration rolls and we would be voting at the nearest Federal building instead of at the local precinct. We have statewide/district wide elections for Federal office holders.
Okay, then let's change my statement to say that Federal law takes precedence over state law with regard to elections for Federal offices.
Over in Lake County Indiana the Democrats once used the list of names from a Puerto Rican graveyard!