Democrat establishment flexes dominance as insurgents fall and GOP bench thins in deep blue stronghold

Massachusetts Democrats rewarded incumbency in marquee primaries Tuesday, but the clearest message came in the state’s generational showdown, with 80-year-old Sen. Ed Markey routing moderate Democratic Rep. Seth Moulton, 47, after Moulton argued it was time for the party to "pass the torch."

Tuesday night's results underscored Democratic dominance in the deep-blue state rather than a single ideological sweep. Voters backed established incumbents across the party’s factions and selected a...