Tennessee Code Title 2. Elections § 2-15-206

(1) If an alternate elector is present to vote, by electing an alternate elector for the vacant position;

(2) If an alternate elector is not present to vote, by electing any resident citizen of the state to fill such vacancy;

(3) If the vacant position is that of an unpledged elector and the alternate elector for that vacant position is not present to vote, or if there otherwise are no alternate electors eligible for the vacant position under subdivisions (b)(1) and (2), by appointing any immediately available individual who is qualified to serve as an elector and has been chosen through nomination by and plurality vote of the remaining electors, including nomination and vote by a single elector if only one (1) remains;

(4) If there is a tie between at least two (2) nominees for substitute elector in a vote conducted under subdivision (b)(3), by appointing an elector chosen by lot from among those nominees;  or

(5) If all elector positions are vacant and cannot be filled pursuant to subdivisions (b)(1)-(4), by appointing a single presidential elector, with remaining vacant positions to be filled under subdivision (b)(3) and, if necessary, subdivision (b)(4).