Ariz. Const. art. 7, § 18

The name of any candidate for United States senator from Arizona shall not appear on the ballot if, by the end of the current term of office, the candidate will have served (or, but for resignation, would have served) in that office for two consecutive terms, and the name of a candidate for United States representative from Arizona shall not appear on the ballot if, by the end of the current term of office, the candidate will have served (or, but for resignation, would have served) in that office for three consecutive terms. Terms are considered consecutive unless they are at least one full term apart. Any person appointed or elected to fill a vacancy in the United States congress who serves at least one half of a term of office shall be considered to have served a term in that office for purposes of this section. For purposes of this section, terms beginning before January 1, 1993 shall not be considered.