2026 Senate Battleground Monitor

Reading this dashboard

• Polling bars show each race's most recent public poll or polling average, not a projection. A stale tag flags any race without an independent poll in the last several weeks.
• Betting markets show Polymarket's live implied win probability, checked once at the "as of" time above — these move continuously and thinner-volume markets (noted per race) can swing on small trades, so treat them as a sentiment check, not a forecast.
• Inside Elections notes call out the race's current IE rating and, where IE has published a rating change or standalone analysis in roughly the last 45 days, what changed and why. Where no recent single-race piece exists (Maine, Michigan), that's stated explicitly rather than substituting another outlet's take.
• TV ad spend bars use AdImpact's fall TV reservations (Aug 19, 2026) where available — the one figure tracked the same way across every race — and fall back to cumulative outside-group commitments or the most recent post-primary actuals where AdImpact didn't cover a race. Each card's source line spells out which basis applies and adds a most-recent-activity line drawn directly from FEC.gov's independent-expenditure filings (Schedule E), pulled via a registered FEC API connection rather than press summaries — this layer refreshes on a rolling few-day lag as new 24/48-hour reports are filed, faster than AdImpact's one-time snapshot. It captures only express-advocacy independent expenditures, not the 501(c)(4) "issue ad" spending AdImpact also tracks, so the two figures measure related but distinct things and shouldn't be summed together. Combined tracked spend is a floor, not a ceiling — real gaps remain (Michigan's Democratic total, for one) where even outside groups' own disclosures don't fully reconcile.