BOSTON -- Gov. Deval Patrick launched his toughest attack on his Republican opponent on Wednesday, accusing Charlie Baker, former president of Harvard Pilgrim Health, for not doing more to keep health care costs down.

The attack comes as Patrick and the Legislature are being pummeled by small businesses that are angry about the double-digit increases in their insurance premiums.

Blackstones of Beacon Hill is a small gift shop run by two owners who said they can't afford to hire anyone full time because of the cost of health insurance. Just to insure himself, owner Mark Duffield said it costs him $800 a month.

"We only have part-timers that come in when we need it. Jennifer and I basically run the business by ourselves," he said.

"We're forced to look only at people we can hire on the weekends because they have full time jobs somewhere else and they're getting their insurance through somebody else," Jennifer Hill said.

Small businesses, which employ 85 percent of Massachusetts workers, aren't expanding or hiring, which was Gov. Deval Patrick's message on Wednesday, telling legislators they have to cap hospital and doctor fees because starting April 1, he's capping health insurance premiums.

"In Pittsfield, a broker saw increases of more than 90 percent this month. In Lawrence, a self-employed mother saw her premium up to 44 percent," Patrick said.

But Patrick's plan to keep premiums under a 5 percent growth rate is meeting with outrage by insurers who want 8 to 32 percent hikes.

"If it costs Dunkin Donuts a dollar to put a cup of coffee out, and government says you can only charge 50 cents. Pretty soon, our local Dunkin Donuts isn't going to exist. This is a very perilous path, I would say," said Lora Pellegrini of the Massachusetts Association of Health Plans.

Hospitals and doctors, in turn, pass the blame back to government programs like Medicare and Medicaid.

"Government doesn't pay its fair share of its cost and so that 130 percent premiums and large numbers are a cost shift to the private sector because government isn't even paying its tab," said Lynn Nicholas of the Massachusetts Hospital Association.

But the heaviest attack came from Patrick who questioned gubernatorial Republican challenger Charlie Baker's reign as head of Harvard Pilgrim Health when there were double-digit premium increases annually.

"Every time something has to be done and has to be done with some urgency. Putting something on the line for regular people, the challengers and he's one of them are missing in action and they're missing in action today," Patrick said.