This top data scientist’s (non-AI) model finds Republicans have just one chance in six of holding Senate

Northwestern University professor Thomas Miller’s political model gives Republicans a one-in-six chance of holding the Senate. The forecast stands out because it relies on prediction market prices and frequently updated information rather than depending mainly on traditional voter surveys.

A forecast built around live market signals

Miller’s approach draws on prediction markets, which have generally provided a stronger guide than polls, according to the source material. His model is updated as new information becomes available, making it more current than forecasts based on less frequently changing survey data.

It also evaluates Senate contests together. Instead of treating each race as an isolated contest, the model adjusts the outlook for individual races using information from all the other Senate races. That approach is designed to capture the relationship between contests when estimating the overall balance of power.

Why the forecast is being watched

Miller has previously attracted attention for making calls that differed from the prevailing political consensus. Before the January 2021 Senate elections in Georgia, polls and pundits expected relatively easy Republican victories. Miller instead forecast a Democratic sweep, which occurred.

He also correctly predicted Donald Trump’s victory in 2024. Those past calls have increased interest in his latest assessment, although the source does not provide further details about the individual races behind the one-in-six estimate.

What the model indicates

The forecast points to a difficult path for Republicans seeking to retain Senate control. Its emphasis on prediction markets, current data and interconnected contests offers a different perspective from conventional polling-based analysis.

For now, the central takeaway is the probability itself: Miller’s model assigns Republicans only a one-in-six chance of holding the Senate.