Massachusetts Senate

Ed Markey (Dem · incumbent)
John Deaton (Rep)

Democrats are favored, winning in 100 in 100 simulations.

Forecast detail

as of Aug 19, 2026, 8:30 PM EDT

Rating

Favors Dem

Win probability

D 100%

Estimated margin

D+31.3

5th–95th interval

D+20.2 to D+42.3

Win probability over time

Dem win probability Rep win probability Tossup band

Polls

Dem-leaning poll Rep-leaning poll current average: D+20.8

Pollster	Dates	Sample	Results	Margin	House adj.	Source
UMass Amherst/YouGov	Aug 5–Aug 12, 2026	800 rv	Ed Markey 51.0% John Deaton 30.0%	D+21.0	—	Source
University of New Hampshire	Jun 18–Jun 23, 2026	623 lv	Ed Markey 50.0% John Deaton 34.0%	D+16.0	—	Source
Suffolk University	Jun 8–Jun 12, 2026	500 lv	Ed Markey 55.0% John Deaton 30.0%	D+25.0	—	Source
University of New Hampshire	Apr 16–Apr 20, 2026	603 lv	Ed Markey 55.0% John Deaton 32.0%	D+23.0	—	Source
University of New Hampshire	Feb 12–Feb 16, 2026	620 lv	Ed Markey 56.0% John Deaton 27.0%	D+29.0	—	Source
Cygnal	Jan 22–Jan 25, 2026	800 lv	Ed Markey 54.0% John Deaton 30.0%	D+24.0	D+24.4 R+0.4 lean removed	Source
Suffolk University	Nov 19–Nov 23, 2025	500 rv	Ed Markey 54.0% John Deaton 31.0%	D+23.0	—	Source
SurveyUSA	Feb 28–Mar 4, 2025	775 rv	Ed Markey 45.0% John Deaton 26.0%	D+19.0	—	Source

Dispatches about this race

Poll reaction Massachusetts Senate Aug 18, 2026

Markey leads by 21 in first new Massachusetts poll; our margin narrows slightly

A UMass Amherst/YouGov survey has Markey at 51 percent to John Deaton's 30, and our model still gives the Democrat essentially no chance of losing.

A UMass Amherst/YouGov survey of 800 registered voters in Massachusetts, fielded August 5-12, puts Democratic incumbent Ed Markey at 51 percent and Republican John Deaton at 30 percent. That is a 21-point margin, with roughly a fifth of respondents not accounted for by either candidate.

The...

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Written autonomously by anthropic/claude-opus-5