Democrats flip to Senate favorites for the first time

Democrats take a narrow lead

Democrats have moved ahead in prediction markets for control of the U.S. Senate after the 2026 midterm election, according to Decrypt. Kalshi and Polymarket contracts put their chances at roughly 51%, against 49% for Republicans—the party’s first lead in those markets’ tracking of the race.

The timing of that snapshot matters: Decrypt’s report is dated Mar 16, 2026, and describes prices as of late Sunday. Although the supplied headline carries an Oct 8, 2026 · 11:54 PM ET publication timestamp, the underlying material does not establish that those prices remained current in October.

Iran tensions accompany the repricing

The reported 51% probability compares with just 18% a year earlier. Kalshi spokesperson Jack Such told Decrypt that Democrats had gained about 11 percentage points since American military involvement in Iran began roughly 16 days before the report. That increase marked an acceleration of a shift already underway over recent months, alongside escalating U.S.-Iran tensions; it does not establish that the conflict alone caused the move.

The change challenged expectations that Republicans would retain the Senate. According to Decrypt, the chamber’s electoral map had been considered favorable to President Donald Trump’s party, even as Republicans were widely expected to face a difficult contest to keep the House. On Myriad Markets, owned by Decrypt parent company Dastan, a separate contract put the chance of Democrats sweeping the 2026 midterms at about 50-50.

Trading activity had increased as the Senate contest tightened. Kalshi’s control contract had recorded more than $2.3 million in volume, while Polymarket’s equivalent had attracted close to $900,000, according to Decrypt. The outlet described those totals as relatively modest compared with traditional financial markets.

These contracts express traders’ collective expectations, rather than a settled electoral outcome. Decrypt cited the markets’ anticipation of a Trump victory in the 2024 Presidential Election as an example of a correct political forecast. With the 2026 midterms still months away at the time of its report, however, the narrow Senate spread left considerable room for repricing as political sentiment, economic conditions and global events changed.

What it means for prediction markets

• The lead is marginal: A 51%-49% split makes Democrats the favorites, but leaves Senate control priced as nearly even.
• The shift is substantial: The rise from 18% a year earlier, including about 11 percentage points over roughly 16 days, shows how sharply expectations changed.
• The contracts differ: Myriad’s Democratic-sweep market measures a broader outcome than Senate control and is not a direct equivalent.
• Snapshot dates are essential: The supplied evidence supports a March market reading, not a verified October update.