By Andrew Firestone

How much is the power of incumbency worth? In a rematch for a Somerville state senate seat decided by only 170 votes four months ago, Senator Sal DiDomenico and Timothy Flaherty, both Democrats, are about to find out.

DiDomenico, former chief of staff for the previous senator Anthony Galluccio, defeated Flaherty in April and the two are now set for a Sept. 14 rematch. The district includes two precincts in wards one and two in Somerville.

In his first few months in office, DiDomenico a former Everett alderman, said he has worked tirelessly, taking only four days off since January 8 while amassing a “a good record of accomplishment at helping people in my district.” Facing earlier criticism that he had not made his voice heard on amendments to the state budget, DiDomenico said that he secured $3.1 million in funding for his district through his eleventh hour work.

“We did not sit on our hands, we did not say we were new. I knew how the building worked, I knew how to get things done and went right to work,” said DiDomenico.

The April special election was necessary after Galluccio was sentenced to one year in jail for a probation violation in connection with a hit and run accident. Galluccio was released from jail last month.

Flaherty must close the 170-vote gap after DiDomenico has spent four months securing endorsements from labor and party leaders.

Flaherty, of Cambridge, attacked DiDomenico as being in “lockstep” with leadership on Beacon Hill, saying “it is very important to be an independent voice in the state senate.” A 10-year veteran of Norfolk County District Attorney’s office, Flaherty said he would use “critical judgment” on every issue he faces.

“I’m driven by evidence,” he said. “I’m not driven by some person or some special interest telling me this is how particular issue favors them.”

Flaherty brought up the gaming bill as his evidence for what was wrong on Beacon Hill. “Oftentimes… in the state senate, decisions are made in conference committees and behind close doors and they are not subject to the public scrutiny.”

“I don’t think that’s the way our democracy was founded,” he said.

DiDomenico, who voted in favor of the gaming bill vetoed by Governor Deval Patrick a few weeks ago said was not in favor of the contentious slot parlors.

“The gaming bill itself is bringing in 15,000 jobs, revenues of close to $400,000 million and something of that magnitude you can’t pass up at this time,” he said regarding the economic downturn. “People need jobs.”

Flaherty said he would create jobs by giving tax credits to companies who make infrastructure for wind and solar powering, calling the Mystic River an “ideal location” due to skilled labor and an educated workforce.