This requires no explication:
JON MEACHAM: So do you believe President Trump is an illegitimate president?"
CARTER: Based on what I just said, which I can't retract. [laughter]
Never before in modern times has a former president declared a current "president" illegitimately elected.
Because no other "president" in modern history has been illegitimately elected, except of course Bush 43 and Bush v Gore and halting the count of black votes in Broward County.
Never forget. And thanks Jimmy Carter.