Cambridge lawyer Dennis A. Benzan declared his candidacy this week for the Mass. Senate seat vacated by recently imprisoned Anthony D. Galluccio.

Benzan is now one of a half-dozen candidates vying for the seat in the special election, which is scheduled for May 11. The primary for the special election is slated for April 13.

Benzan, a Democrat, told The Crimson that he made the decision to run last week, after Republican Scott P. Brown handily won the U.S. Senate seat that had been occupied by Democrat Edward M. Kennedy ’54-’56 since 1962.

“That night I felt so much frustration,” Benzan said regarding the election upset. “I had already been considering running, and that’s what made me decide.”

Benzan said he plans to highlight economic concerns that he said Martha Coakley, Brown’s Democratic opponent, neglected in her campaign. He added that he wants to reach out to Democrats who did not go to the polls for Coakley, and said that he will emphasize his personal background throughout the campaign.

“I grew up in Cambridge. I don’t know one individual in my neighborhood who went to Harvard or MIT,” Benzan said. “I know plenty of my peers who went to prison and became addicted to drugs.”

“I’m an example to children of what they’re capable of accomplishing. In the process of doing this campaign, I will inspire younger people to feel again that they can participate in the political process,” he added.

Brian McNiff, a spokesperson for Mass. Secretary of State William F. Galvin, told The Crimson that six candidates—Michael J. Albano, Andrew Bertinalli, Cambridge City Councillor Marjorie C. Decker, Daniel C. Hill, Timothy Flaherty, and Benzan—have filed the necessary paperwork to run in the Democratic primary. McNiff added that one Republican, Diane Carell, and one Independent, John Cesan, have also declared their intent to run.

Despite the long list of competitors, Benzan told The Crimson, “I’m the candidate to watch.”

Benzan ran for the state House of Representatives in 1996 and 1998. In 1998 he lost to Jarrett T. Barrios ’90, who went on to hold the Middlesex, Suffolk, and Essex state Senate seat before Galluccio was elected.

Galluccio himself was sent to the state Senate by special election, after Barrios stepped down to run a health care company in 2007.

Galluccio resigned the seat earlier this month after he was sentenced to a year in jail for failing a series of breathalyzer tests less than three days after he was put on probation for an October hit-and-run accident in Cambridge. He plans to appeal his jail sentence and will be represented by Harvard Law School Professor Charles J. Ogletree, according to the Boston Globe.

The candidate elected to succeed Galluccio will represent parts of Cambridge and several surrounding towns in the state Senate.

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