Reading the 2026 Senate map

Behind the Ballot is built on one rule: every number traces to a public source. This first look walks through how to read a race page.

Polling vs. forecast

A polling average is a snapshot of what pollsters measured, weighted by recency and pollster quality. The forecast goes further — it blends that polling average with fundamentals (partisan lean, incumbency, finance) and runs a Monte Carlo simulation to turn a margin into a win probability with a range.

A 60% win probability is not a prediction that someone wins by a lot. It means: across many simulated election nights — including good and bad national environments — that candidate wins about 6 times in 10.

Where the numbers come from

Finance figures come from the FEC, polling from 538, demographics from the Census ACS, and ideology from Voteview. The sources page lists every feed with its license and freshness floor. If a feed goes stale, we flag the figure rather than show it silently.

Caveats are a feature

On the maps page we show several fairness measures side by side precisely because they disagree. No single metric proves a map is gerrymandered — so we never reduce it to one verdict.