Healey's announcement, in late January, cleared the field of previously declared Democratic candidates. Her fundraising prowess and national stature, sharpened during Trump's presidency when she often challenged his administration in court, has made her a household name among commonwealth Democrats who believed she represented the party's best chance to unseat Baker.

In addition to the top of the Democratic ticket, the party's congressional delegation is all but settled following recent cycles of upheaval. None of the nine members of Massachusetts' all-Democratic US House delegation are facing a primary challenger this year.

So, much of the intrigue Tuesday came from a pair of primaries that might not have been close -- or even contested, in one case -- had Baker sought a third term.

On the Republican side, Diehl emerged from a contentious contest with Doughty, who had argued that he represented the GOP's best chance to defeat Healey in November. (Diehl had the state party's endorsement, but Doughty secured enough delegates at its May convention to make the ballot.)

Doughty -- who has said he voted for Hillary Clinton in 2016 and Trump in 2020 -- got a late boost from influential conservative radio host Howie Carr, who, echoing the candidate's electability argument, backed Doughty over Diehl.