Senate odds drift toward the GOP as midterm pricing softens for Democrats

Democrats’ Senate pricing slips

Democrats’ chances of controlling the Senate declined by approximately 3 percentage points over the week, leaving them at about 3-in-5 on the combined Kalshi/Polymarket board, according to the supplied market summary dated Oct 12, 2026, at 10:09 PM ET.

That movement shifted pricing toward the GOP, although Democrats remained favored in the combined reading. The summary does not provide separate prices for Kalshi and Polymarket.

The Democratic side of the Michigan Senate market also weakened, falling 5 points. Its endpoint is missing from the truncated summary, so the material does not establish the resulting probability or which party was favored in that race.

The accompanying excerpt from defirate.com contains no Senate reporting or explanation for the changes. The available material therefore supports a report on the direction and size of the moves, but not their causes.

What it means for prediction markets

• A narrower Democratic advantage: The approximately 3-point weekly decline leaves Senate-control pricing at about 60% for Democrats, rather than indicating a GOP lead.
• Michigan moved further: Its Democratic contract fell 5 points, compared with the approximately 3-point decline in the broader Senate-control measure. The missing endpoint limits further comparison.
• Venue differences remain unknown: The combined Kalshi/Polymarket reading does not show whether both platforms moved by similar amounts.