NO one knows, as it has Never been publicly released, what, if any political party The King belonged to. 43 years after his passing it's still a mystery.
Documented Arguments have been made for Both sides...
50's: Elvis on the record supported Stevenson (opposed to Ike).
60's: JFK Signed Picture to Elvis & the Col. Elvis' admired & supported JFK & RFK (JFK assassination, Elvis cried)
60's: Elvis' CA. home containing LBJ keepsakes (that John Lennon took issue with Elvis over!)
60's/70's: Nixon's 'thank you' letter to Elvis / Elvis visits Tricky Dick at the White House & gifts him.
70's: Elvis Meets George Wallace, Bush II & Carter.
70's: Elvis regularly calls Carter to the Presidents personal White House Hot line. (Carter was quoted as saying "a lil' too regularly.")
2018: Priscilla & Lisa Marie Decline to go to White House to accept 'Medal Of Freedom' from Trump. (EPE Executor Jack Soden filled in.)
Ancestry: Elvis' Presidential Relatives; Abe Lincoln & Jimmy Carter. Genealogists discovered that the great-great-grandfather of our 16th President, Abe Lincoln, was Isaiah Harrison, an ancestor to Elvis. The 39th President, Jimmy Carter is a 6th cousin, once removed from Elvis.