Incumbent Sen. Ed Markey holds a commanding position in the Massachusetts Democratic Senate primary, reflecting his long congressional tenure and broad backing from established party networks and progressive voters. Recent polling has narrowed his lead over Rep. Seth Moulton to five points in an Emerson College survey released in early May, with 29 percent of likely primary voters still undecided, which has modestly lifted Moulton's implied probability while leaving minor candidates Alexander Rikleen and Ayanna Pressley with negligible support. This tightening follows earlier surveys showing double-digit advantages for Markey and underscores how the September 1 primary timeline and undecided bloc could influence final outcomes before voters finalize their choice among the field.