In the uncompetitive 2026 Massachusetts Senate contest, where incumbent Democrat Ed Markey holds a wide lead over Republican John Deaton according to recent polling, trader consensus clusters around 2.65M–2.95M total votes cast. The September 1 Democratic primary between Markey and Seth Moulton produced limited enthusiasm, consistent with Secretary of State William Galvin’s assessment that it would not generate unusually high participation. Typical midterm drop-off in a safely Democratic state, combined with reliance on early voting volumes and mail ballot returns ahead of the October 17 start for in-person early voting, keeps leading ranges tightly matched. Developments that could shift probabilities include stronger-than-expected early or mail turnout, national political events influencing mobilization, or Election Day conditions affecting participation rates.