Sal N. DiDomenico won the Democratic primary for a State Senate seat last night, earning the chance to run in the November general election and likely retain the seat he has held since May.

DiDomenico defeated Timothy R. Flaherty for the Middlesex, Suffolk, and Essex seat by a margin of approximately 178 votes out of over 10,000 cast, according to Flaherty spokeswoman Dorie R. Clark.

In his hometown of Cambridge, Flaherty took far more votes—2,592 to DiDomenico’s 993.

In the 13 Boston precincts—including parts of Allston, Brighton, and Charlestown—which are included in the district, Flaherty topped DiDomenico with 1,490 votes to the incumbent’s 956. However, DiDomenico had strong results in Everett, where he is a former City Councillor; he picked up over 2,000 votes more than Flaherty there.

DiDomenico defeated Flaherty and four other Democratic candidates for the seat in a special primary held last April, after former State Senator Anthony D. Galluccio resigned the seat upon being sentenced to a year in jail for an alcohol-related probation violation.

Flaherty was the closest of the five runners-up in the April race, losing to DiDomenico—who previously served as Galluccio’s chief of staff—by about 135 votes.

He declared on the day after his loss that he would run again in the fall, when the normal election schedule dictates that the seat is up for grabs again.

“It was an emotional evening,” Clark said tonight after Flaherty conceded at 9:15 p.m. “This was the second time we had such a close race.”

DiDomenico will now face the sole Republican candidate, Barbara T. Bush of Charlestown, in the general election. The winner will serve a two-year term on Beacon Hill.

Other contested races on Cambridge residents’ ballots in yesterday’s primary included State Auditor, which Democrat Suzanne M. Bump and Republican Mary Z. Connaughton won in their respective races, and the Democratic race for treasurer, won by Steve Grossman.

—Staff writer Julie M. Zauzmer can be reached at jzauzmer@college.harvard.edu.

This article has been revised to reflect the following correction:

CORRECTION: September 15, 2010

An earlier version of the Sept. 15 news article "DiDomenico Wins Democratic Primary" stated that only 3,585 of Cambridge's registered voters cast votes in the in the DiDomenico-Flaherty race, creating a turnout of 5.87 percent. In fact, there were a total of 9,073 ballots cast in the city for a voter turnout of about 15 percent.