The Phoenix has learned that state senator Sal DiDomenico will announce later today that Congressman Michael Capuano, Somerville mayor Joe Curtatone, and Boston city councilors John Connolly and Sal LaMattina have endorsed him for re-election this fall.
DiDomenico, who recently won the special election to succeed Anthony Galluccio, is facing an immediate rematch with attorney Tim Flaherty, who finished second in the special-election Democratic primary.
Today's powerhouse endorsements cap a series of endorsements from around the district -- particularly outside DiDomenico's home base of Everett.
The early timing of the endorsement rollout is probably intended to pressure Flaherty into abandoning his challenge. Tomorrow is the deadline for candidates to remove themselves from the official list to appear on the September 14 primary ballot.
However, the major new DiDomenico endorsers do not include former backers of Flaherty, so it is not yet clear whether he is losing any of his previous support.