Tennessee Constitution Art. III, § 12

In case of the removal of the Governor from office, or of his death, or resignation, the powers and duties of the office shall devolve on the Speaker of the Senate; and in case of the death, removal from office, or resignation of the Speaker of the Senate, the powers and duties of the office shall devolve on the Speaker of the House of Representatives.

Whenever the Governor transmits to the Secretary of State, the Speaker of the Senate, and the Speaker of the House of Representatives, a written, signed declaration that the Governor is unable to discharge the powers and duties of the office, the powers and duties of the office of Governor shall be temporarily discharged by the Speaker of the Senate as Acting Governor, or if that office is unoccupied, then by the Speaker of the House of Representatives as Acting Governor, until the Governor transmits to the same officials a written, signed declaration that the Governor is able to discharge the powers and duties of the office.

Whenever a majority of the commissioners of administrative departments of the Executive Department transmits to the Secretary of State, the Speaker of the Senate, and the Speaker of the House of Representatives their written, signed declaration that the Governor is unable to discharge the powers and duties of the office, the Speaker of the Senate shall immediately assume the powers and duties of the office as Acting Governor, or if that office is unoccupied, then the Speaker of the House of Representatives shall immediately assume the powers and duties of the office as Acting Governor, until the Governor transmits to the same officials a written, signed declaration that the Governor is able to discharge the powers and duties of the office.

Whenever a Speaker is temporarily discharging the powers and duties of the office of Governor as Acting Governor, such Speaker shall not be required to resign the Speaker's position as the Speaker or to resign as a member of the General Assembly and shall retain the Speaker's salary and not receive the Governor's salary, but such Speaker shall not preside as Speaker or vote as a member of the General Assembly during the time the Speaker is Acting Governor.