Incumbent Sen. Ed Markey commands trader consensus at 86.5% implied probability to win Massachusetts's Democratic Senate primary on September 1, driven by his strong incumbency advantage and consistent poll leads over Rep. Seth Moulton, the primary challenger framing the race around generational change. A Suffolk University/Boston Globe poll released April 15 (conducted April 9-13) shows Markey ahead 47%-30% among likely Democratic primary voters, with 20% undecided likely consolidating toward the veteran senator who fended off a competitive 2020 challenge from Joe Kennedy. Rep. Ayanna Pressley's March endorsement after opting out further bolsters Markey, limiting her to 2.3%, while state Rep. Alexander Rikleen trails at 0.4% amid low name recognition. Moulton's 11.5% reflects fundraising and North Shore support but faces an uphill battle in the progressive-leaning electorate.