Conn. Const. art. fourth, § 18

In case of the death, resignation, refusal to serve or removal from office of the governor, the lieutenant-governor shall, upon taking the oath of office of governor, be governor of the state until another is chosen at the next regular election for governor and is duly qualified. In case of the inability of the governor to exercise the powers and perform the duties of his office, or in case of his impeachment or of his absence from the state, the lieutenant-governor shall exercise the powers and authority and perform the duties appertaining to the office of governor until the disability is removed or, if the governor has been impeached, he is acquitted or, if absent, he has returned. (When president pro tempore to become lieutenant-governor or act as lieutenant-governor.)