US midterms 2026: What polls and prediction markets indicate about Congress

With the US midterm elections approaching, President Donald Trump and congressional Republicans face a closely watched electoral contest. Economic concerns, the cost of living and foreign policy developments are among the issues shaping the political debate. Historical trends have also often favoured the opposition party during midterm elections.

Poll aggregators, election analysts and prediction markets are tracking the battle for control of Congress, with their assessments offering different projections for the House of Representatives and the Senate.

What is at stake in the US midterm elections?

All 435 seats in the US House of Representatives are up for election. Either party needs at least 218 seats to secure a majority.

In the Senate, 35 seats are being contested through regular and special elections. Republicans are defending 22 seats, while Democrats are defending 13.

Democrats would need a net gain of four seats to reach a 51-seat majority, as Vice President JD Vance can break tie votes in favour of Republicans.

What do poll aggregators and election analysts say?

According to the figures provided, RealClearPolling and other polling aggregators show Democrats leading the generic congressional ballot by 7.5 to 8.3 percentage points. Their projections suggest Democrats could gain at least 10 seats in the House, putting a majority within reach.

Nonpartisan election handicappers, including Cook Political Report and Sabato's Crystal Ball, have also classified enough competitive House districts as favourable to Democrats to indicate a potential takeover.

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The Senate contest is more closely divided. Polling models indicate a narrow path for Democrats to reach a 50- or 51-seat position, depending on the results in several competitive states.

Maine, Texas, Ohio and Iowa are among the key battlegrounds identified in the supplied analysis. Georgia, Michigan and New Hampshire are also important to the parties' efforts to secure control. Election handicappers have rated four to five Republican-held Senate seats as vulnerable or toss-ups.

What do prediction markets indicate?

Prediction markets assign a higher probability to Democratic control of the House than the Senate.

Kalshi places the probability of a Democratic House majority at 88–91 per cent, while Polymarket puts it at 90–92 per cent.

For the Senate, Kalshi places the probability of Democratic control at 62–66 per cent, while Polymarket puts it at 64–65 per cent.

The figures provided show a difference in the outlook for the two chambers, with the Senate contest appearing more closely divided in the available estimates.