Coakley's campaign released a web video on Monday criticizing Grossman for not signing a so-called "people's pledge" that would limit ads by independent expenditure groups that can raise and spend unlimited cash on behalf of or against candidates.
The TV ad, paid for by the pro-Grossman SuperPAC Mass Forward, criticizes Coakley for not supporting a Gov. Deval Patrick's proposal to limit individuals to one gun purchase per month. The ad calls Coakley, the state's attorney general, the "wrong choice for governor."
SuperPACs by law must operate independently from candidates.
Grossman, the state treasurer, Coakley and Don Berwick are competing for the Democratic nomination for governor.