BOSTON - Ginning up a crowd outside a Ben & Jerry's scoop shop on Newbury Street, Ben Cohen and Jerry Greenfield riff off each other like the long-time partners that they are.

"We've been constituents of Bernie for over 30 years," Cohen says, referring to Vermont senator and Democratic presidential candidate Bernie Sanders.

"Thirdy years!" Greenfield exclaims.

"We've seen him in action, and he's the most incredible presidential candidate we've ever run into in our lives," Cohen continues.

"In our lives!" screams Greenfield.

Then they get around to the serious business; handing out free "Bernie's Yearning" ice cream sundaes.

Cohen and Greenfield, the founders of Ben & Jerry's Ice Cream, are spending three days in Massachusetts campaigning for Democratic presidential candidate Bernie Sanders in advance of Massachusetts' March 1 presidential primary. Sanders, a longtime independent U.S. senator from Vermont who enrolled as a Democrat in April to seek the Democratic presidential nomination, is in a tight race for with former secretary of state, first lady, and U.S. senator Hillary Clinton.

Cohen and Greenfield know Sanders from Vermont, where they founded their business, which they have since sold. Although Ben & Jerry's as a company does not support candidates, the two company founders, who both still work for Ben & Jerry's, are campaigning for Sanders as private citizens. At events, they purchase the ice cream from the store, then donate it to the Sanders campaign.

Cohen invented the original "Bernie's Yearning" ice cream in his kitchen, making just 40 pints of it. It was plain mint ice cream with a solid disk of chocolate covering the top of the pint.

"The solid disk of chocolate represents all the wealth that's gone to the top 1 percent since the recession. On the bottom is the rest of us," Cohen said. "The way you eat it is you take a soup spoon and you whack the chocolate disk into a bunch of pieces, then you mix it around and there you have it - Bernie's Yearning."

The 40 pints were all given away in a contest through Sanders' website. Cohen and Greenfield are now making Bernie's Yearning bowls, and Cohen said he is willing to make a pint of the specialty ice cream for anyone who wins a bowl and brings it to Vermont. Standing outside Ben and Jerry's on Newbury Street in Boston, the two handed out free sundaes of a more mundane style - vanilla ice cream with a chocolate disk.

Greenfield said they have never before campaigned for or created an ice cream flavor for a presidential candidate.

"He's a politician who comes along once in a generation," Greenfield said. "He's not for sale. He's only taking money in small contributions from regular people, not taking any money from special interests."

"Despite what Hillary might be saying, she's financed by corporate interests, by Wall Street, by the pharmaceutical industry. That's who she represents," Cohen said, echoing a common theme of the Sanders campaign.

Cohen and Greenfield have campaigned for Sanders - always with ice cream - in Iowa, New Hampshire and Minnesota. In Massachusetts, they are holding events in Pittsfield, Cambridge and Boston. They will participate in a business event with State Sen. Dan Wolf, D-Harwich on Tuesday.

Sanders, in his campaign, has talked about closing tax loopholes that benefit corporations. While he says he wants to help small business through things like low-interest loans, he also advocates raising the minimum wage to $15 an hour - something many small businesses oppose.

Ryan Midden, general manager of Ben and Jerry's in Boston, who supports Sanders as an individual, said the store pays a $9.25 minimum wage, but he still supports Sanders' call to raise the minimum wage above that.

"Were ready to take on that challenge," Midden said. "We're in support of raising the minimum wage. We want people to get a fair wage for what they're doing."

Greenfield said the point of government "is to set a level playing field. ... Now if you have some businesses doing the right thing and paying $15 an hour, they're trying to compete with business that are not paying that much. That makes it difficult."