SOUTH PORTLAND — The four Democrats running for Maine’s open U.S. Senate seat said Congress is not doing enough to protect small businesses and the middle class.

Maine Sen. Cynthia Dill, D-Cape Elizabeth, former Secretary of State Matthew Dunlap, state Rep. Jon Hinck, D-Portland, and businessman Benjamin Pollard appeared this morning at a forum sponsored by the Portland Regional Chamber.

The four are running in the June 12 Democratic Senate primary, and the winner will face the Republican nominee and former Gov. Angus King, who is running as an independent. All six Republican candidates are scheduled to attend a similar forum at the Sable Oaks Marriott next Wednesday.

The Democratic candidates agreed that the federal government can do more to stimulate job creation, such as by weatherizing homes and businesses, and free up investment capital that has been sitting on the sidelines since the Wall Street meltdown in 2008.

“The federal government can do an awful lot more to shore up the availability of that credit,” Dunlap said.

Hinck said the key is to shore up the middle class so businesses can make the case for investment. “The capital is ready to go…. It needs demand.”

Pollard said government incentives for investments such as home remodeling could get capital back in circulation.

Dill said she supports improved regulation of Wall Street to protect small businesses. Deregulation, she said, “led to the economic collapse and small business people are now the ones paying the price.”

The candidates also said small businesses need more protection from unfair global trade, and a tax code that doesn’t favor the wealthiest 1 percent at the expense of small businesses and the middle class.

“General Electric is paying nothing in taxes right now,” Hinck said. “Why are the largest entities able to escape it?”

While the forum focused on issues facing small business, it began with a recurring question about King.

“How are you going to beat Angus King?” asked Chris Hall, executive vice president of the chamber. “I asked for questions from the audience and it was the question I got from everybody.”

Dill said she would contrast her record of support for the middle class and economic justice with King’s record, which includes opposition to minimum wage increases and expanded family medical leave.

Dunlap, on the other hand, said voters are tired of negative campaigns and he would offer a positive message about his plans for restoring prosperity.

Hinck said he would focus the debate on the political dominance of wealthy business interests and his experience as an activist and lawyer taking on corporations.

Pollard said his youthful idealism would offer the clearest alternative and would bring in new voters.