SDCL § 12-24A-4: Vacancy of presidential elector--Causes--Resignation.

The office of presidential elector becomes vacant if the elector:

(1) Dies;

(2) Resigns;

(3) Fails to qualify, as provided by law;

(4) Fails to appear at the designated time and place of the meeting;

(5) Refuses to vote;

(6) Attempts to cast a blank ballot; or

(7) Except as provided for in § 12-24A-8, attempts to vote for any candidate other than the candidate whose slate of electors received the highest number of votes in the state's general election.

If a presidential elector casts a ballot that results in the office of elector becoming vacant, the ballot may not be accepted or counted. An elector may resign the office of presidential elector by submitting a letter of resignation to the secretary of state.