All expenses incurred by the committee, including salaries and expenses of employees, shall be paid upon voucher forms as provided by the auditor and signed by the chairperson or vice chairperson of the committee and attested by the secretary of the committee, and the authority of the chairperson and secretary to sign vouchers shall continue until their successors are selected after each ensuing session of the legislature. Vouchers may be drawn on funds appropriated generally by the legislature for legislative expenses or upon any special appropriation which may be provided by the legislature for the expenses of the committee or both.