This market will resolve according to the party that wins control of the Arizona State Senate in the 2026 Arizona midterm election.

A party wins control of the Arizona Senate if it wins a majority of the chamber’s voting seats. If no party wins a majority of voting seats, the chamber will be deemed controlled by the party with which the first selected President of the State Senate that convenes after the specified election is affiliated. If no such President of the State Senate is chosen by March 31, 2027, 11:59 PM ET, this market will resolve to "Other".

The following rules govern the counting of seats for determining which party wins control of the chamber.

All regular and special Senate elections that determine representation in the following State Senate and are scheduled to take place in November 2026 as of October 31, 2026 are included. Runoffs for qualifying elections will determine attribution of the relevant seat, even if they take place after November 2026. Vacant seats for which no election or special election to fill the seat is scheduled to take place in November 2026 as of October 31, 2026 will be treated as held by the party affiliation of the most recent member to hold that seat.

For seats contested in the specified election, seats are attributed to the party under which the member was elected. If a member-elect changes party affiliation, or vacates their seat, between election day and the formal organization of the Chamber, the seat is attributed to the party under which the member was elected.

For seats not contested in the specified election, seats are attributed to the party that holds the seat as of the date of the election. If a current sitting member of the Chamber who is not up for election changes party affiliation or vacates their seat after the date of the election, the seat is attributed to the party under which the member was affiliated at the time of the election.

Members elected as independents who formally caucus with, or, for newly elected members, who announce their intent to caucus with, a party are included in that party’s count. If the caucus decisions of members elected as independents cannot be determined on the date of the election, this market may remain open until the earlier of (i) an announcement from the relevant members of their intents to caucus, or (ii) January 4th, 11:59 PM ET of the following calendar year. If no such announcement is made by January 4th, 11:59 PM ET of the following calendar year, the member will not count towards the seat count of any party.

The resolution sources for this market will be official information from relevant state electoral authorities, the Arizona State Senate, and a consensus of credible reporting.