The Man Who Called Trump’s Win Now Puts Democrats at 78% for the Senate
The first number stopped me: 78%. That is Thomas Miller’s current probability that Democrats will win control of the U.S. Senate next month. Miller is the Northwestern University data scientist whose model called Donald Trump’s 2024 presidential victory. Now his model says the GOP is in trouble.
I did not expect that from him. That is not a reason to believe it. It is a reason to slow down and look at what he is actually measuring.
What the model says
Miller finds Democrats leading in 18 of the 35 Senate races up this year, with Republicans ahead in 17. If those current odds held through Election Day, Democrats would take a 52-to-48 majority, a four-seat swing from the Republicans’ current 53-to-47 advantage.
His estimate is not a poll average. Miller starts with prices from the prediction markets Kalshi and Polymarket, then applies time-series analysis to identify the broader forces moving many races at once. He says those shared movements are likely tied to what Trump says and does.
That is the part worth sitting with. In Miller’s view, Senate races are not moving independently. When voters respond badly to the president, Republican odds fall across the map. When they respond well, they rise across the map. The “Trump effect,” in this reading, is currently working against his own party.
Why this one gets attention
Forecasters are easy to dismiss when they have been wrong. They are also easy to overtrust when they have been right. Miller has a record that makes people pay attention: he correctly forecast Trump’s 2024 win, and he had earlier correctly forecast the 2020 presidential election.
His method is different from the usual mix of polls, fundraising totals, and historical state trends. He treats betting markets as a leading indicator, on the theory that people putting money at risk reveal something that surveys may miss.
That does not make prediction markets wise. They can overreact to news, misprice attention, and reflect the views of people who trade rather than the full electorate. But they do react quickly. And in an election season, quick reactions can show a change before the pollsters catch up.
The cautious part
The number has moved fast. Fortune reported that Miller’s model gave Democrats a 77.6% chance of a Senate majority as of October 23, up from 71.5% on October 14. On September 19, his model still gave Republicans about a 36% chance of holding the chamber.
A ten-point move in five weeks is either a real shift or a market catching up to something. It could also be both. What it is not, yet, is a result.
Miller himself treats the numbers as volatile. The races remain close enough that a few state-level surprises could change the outcome. A model can say Democrats are favored and still be wrong; 78% is high, but it leaves plenty of room for the other 22%.
Other forecasters are less bullish. Decision Desk HQ, for example, gives Democrats a 56% chance of winning the Senate and projects 51 seats. That is still a Democratic edge, but it is a much narrower one than Miller’s.
What it means for voters
For most people, this is not an argument about models. It is about whether the next Senate will make life easier or harder: whether health costs, housing, wages, taxes, and the basic functioning of government get attention or become props in another round of partisan warfare.
A Democratic Senate would not fix those problems by itself. A Republican Senate would not cause all of them. But control of the chamber determines which bills reach the floor, which nominees get confirmed, and how much scrutiny a president faces. Those are practical things.
The interesting possibility in Miller’s data is that voters may be judging the party in power as a whole, not merely evaluating each Senate candidate separately. If he is right, candidates in states far from Washington are paying a price for decisions made in Washington.
What I would watch
I would watch whether the market movement holds after the next round of campaign events, debates, and late-breaking news. I would also watch whether the closer races begin to separate from the pack. A broad national shift can lift a party everywhere for a while. Individual campaigns, money, candidate quality, and local issues still matter when the votes are counted.
The honest answer is that Miller’s forecast is a strong signal, not a verdict. It says the political weather has changed since September. It does not say what the sky will look like on November 3.
Still, there is something notable in the fact that the analyst who saw Trump’s 2024 win coming now sees the president’s party losing ground in Senate race after Senate race. It is a reminder that elections are not fixed by last cycle’s results. Voters are still making up their minds.
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