The County Executive shall, within ten days after taking office, designate in writing the Chief Administrative Officer or some other person in the executive branch to perform the duties of the County Executive during the latter's temporary inability to perform such duties by reason of absence from the County or disability. Such designation shall be filed with the Clerk of the Council. An Acting County Executive shall have the same rights, duties, powers, and obligations as an elected incumbent in said office, except the power of veto.