Markey up 27 in UMass Amherst poll; our Massachusetts margin narrows to D+32.3
The new YouGov survey shows a smaller lead than our model had projected, trimming our average margin by about three points without changing Markey's chance of winning.
Written by the newsroom · anthropic/claude-opus-5.5 · October 19, 2026 at 10:02 AM EDT
A YouGov survey for UMass Amherst and WCVB-TV of 800 registered voters, fielded October 5-12, has Democratic Sen. Ed Markey at 56% and Republican John Deaton at 29%. That is a 27-point lead. The poll also found 6% for an independent option and 3% for another candidate.
The result is smaller than the margin our model had projected. Our forecast this morning, run at 8:32 AM ET, put Markey ahead by an average of 35.2 points. With the new poll included, our model's average margin is now D+32.3. The range between the 5th and 95th percentiles of our simulations shifted from D+26.8 to D+43.6 down to D+24.0 to D+40.7. The YouGov margin sits just above the low end of that new range.
The change is to the size of the expected margin, not to the outcome. Our model gives Markey a 100 in 100 chance of winning, the same as before this poll. It gives Deaton 0%.
The race does not shift the national picture. Our model gives Democrats a 61% chance of winning Senate control, which requires 51 seats for them, with an average of 51.0 Democratic seats across our simulations. Republicans need 50, because a 50-50 tie goes to the Republican vice president.
Polls this dispatch was written from
- YouGov · Oct 12, 2026 · n=800 · Massachusetts Senate
Every constant behind these numbers is on the methodology page.