Eliminate the presidency.
Divide the USA into a half dozen or so regions (northeast, mid-atlantic, etc), and have each set of states elect an executive representative to serve on the federal executive cabinet.
And related advice at nordic graceland:
Put prerequisites on almost all political offices:
Only state governors or senators can run for the executive cabinet, only county EO’s can run for governor, only mayors can run for county EO, etc. Work your way up.