Politics

Balance of Power: 2026 Midterms

Which party controls the United States Senate and the House of Representatives after the 2026 midterm elections? Polymarket lists five combinations as separate markets, and the market is scheduled to end on 2026-11-04.

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Current Probability

Democrats win both chambers

66%

Market-implied probability

  • 24 hours no change

Source

Single source

Key facts

Ends
November 3, 2026
Volume
18.7M

This page describes what the market on Polymarket currently implies. It is not a forecast by The Sweat.

Probability History

Outcomes Market-implied probability

  1. Democrats win both chambers 66% 24 hours: no change
  2. Republicans win the Senate, Democrats the House 27% 24 hours: no change
  3. Republicans win both chambers 9% 24 hours: up 1 pts
  4. Democrats win the Senate, Republicans the House <1% 24 hours: no change
  5. Other <1% 24 hours: no change

Each option is priced on its own, so these may not add up to 100%.

What the Market Thinks

Market-implied probabilities for each combination of party control of the Senate and the House after the 2026 midterms, taken from Polymarket, where every combination trades as its own market. Prices are independent, so they may not add up to 100%.

How It Resolves

This market will resolve according to the party that wins control of the United States Senate and the party that wins control of the United States House of Representatives in the 2026 United States midterm election.

A party wins control of the United States Senate if it wins a majority of the chamber’s voting seats. If no party wins a majority of voting seats, the party that wins control of the chamber is the party that wins half of the voting seats and holds the Vice Presidency. If the outcome remains ambiguous after applying the above criteria, the chamber will be deemed controlled by the party with which the first selected President Pro Tempore of the Congress that convenes after the specified election is affiliated.

A party wins control of the United States House of Representatives 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 elected Speaker of the House of the Congress that convenes after the 2026 midterm election is affiliated.

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

For determining Senate control, all regular and special Senate elections that determine representation in the upcoming 120th Congress and are scheduled to take place in November 2026 as of October 31, 2026 are included. Vacant Senate 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 determining House control, all House elections in the 2026 United States midterm election that elect voting members and determine representation in the upcoming 120th Congress are included. Where a Senate or House seat is decided by a runoff, the runoff result will determine attribution of that seat, even if it takes place after November 2026.

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 Congress, 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 U.S. Senate 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.

Senate and House 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 of the Senate or House 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 United States Congress, and a consensus of credible reporting.

Resolution source: Official 2026 United States midterm election results

Expected resolution: November 3, 2026