Tennessee Code Title 4. State Government § 4-4-115

(a) In the event of the absence, illness or disability of any commissioner or the head of any department, division or agency of the executive department of state government, the governor is authorized and empowered to designate and appoint a qualified person to act in such capacity.

(b) The person so designated shall have all the powers, duties and responsibility provided for such office under the statutes of this state during the time such person is so serving.

(c) This section shall apply to the secretary of state, the comptroller of the treasury and the state treasurer, except as provided for in §§ 8-3-105, 8-4-302 and 8-5-202.