The closely matched Polymarket ranges for total votes cast in Massachusetts' U.S. Senate race reflect expectations of subdued midterm participation in a safely Democratic contest. Incumbent Ed Markey defeated Seth Moulton in the September 1 Democratic primary by roughly 30 points with limited overall enthusiasm, while Republican John Deaton advanced unopposed; recent polling shows Markey leading Deaton by about 20 points. Secretary of State William Galvin has indicated the low-competition general election is unlikely to produce unusually high turnout. Typical midterm drop-off from presidential-year levels, combined with ongoing monitoring of early voting volumes and mail ballot returns ahead of the October 17 start and November 3 election, keeps the leading bins clustered near historical benchmarks around 2.5M–2.9M votes. A surge in independent or Democratic mobilization could shift probabilities higher, while further evidence of voter disengagement would favor the lower ranges.