The U.S. Capitol Building photographed on March 27, 2026 in Washington, DC.
Samuel Corum | Getty Images
The 2026 U.S. midterm elections will be held a week from Tuesday, with Republicans aiming to maintain their majorities in both houses of Congress, but prediction markets show Democrats as a 2-1 favorite to flip both chambers blue.
Speculators on Carsi’s platform give Democrats a 63% chance of winning a majority in both the House and Senate. These odds have remained relatively stable since early October. Meanwhile, there is a less than 10% chance that Republicans will win both chambers of Congress, and a 29% chance that Democrats will win the House while Republicans maintain a majority in the Senate.
Market contracts are settled using official data from the US Congress.
Odds and gambling platforms are not replacements for political polls, as they do not use the techniques used in traditional political polls.
On Sunday, prediction markets had predicted that right-wing candidate Flavio Bolsonaro would likely win Brazil’s presidential election before voting ended, but incumbent left-wing president Lula da Silva was re-elected. This election cycle’s Democratic primaries in some markets also drew criticism for the extremely high odds of winning for some candidates, who ultimately won or lost by a narrow margin.
However, according to the platform, the odds set by the trader often happen in that exact proportion. This essentially means that a candidate with a 20% chance of winning an event contract exchange has a 20% chance of achieving an “upset” victory.
Until early September, Democrats had a less than 50% chance of controlling both houses of Congress, but the odds have increased from about 30% at the beginning of last year due to the outbreak of the U.S.-Iran war and rising gas prices that are hurting consumers.
In the poly market, there is a 65% chance that the Democratic Party will control both houses of Congress.
Opinion polls widely show that Democrats hold the national popular vote in the House of Representatives and will be competitive in a series of red-state Senate races that will determine control of the Senate. But House Speaker Mike Johnson (R-Louisiana) casts doubt on these findings.
“We’ve been going from continent to continent,” he said on a Fox News appearance Monday. “I’m telling you, the polls are inaccurate.”
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