Don Berwick stays away from caffeine.

“Decaf, please,” he reminds a waitress at McKenna’s in Savin Hill, as she goes to refill his cup.

He got off caffeine just before he moved to Washington, D.C. He had a headache for three or four months. And then, it “changed my life.”

“I didn’t like the stimulation all the time,” he says.

On the campaign trail, stimulation can seem like a necessity. The days are long, a never-ending schedule of greeting voters and phoning donors.

No wonder campaigns run on Dunkin’, or a reasonable facsimile. But Berwick does not.

“Part of it is adrenaline,” he says, when asked about his alternative to caffeine. “The best part of it to me is when you’re in a room with people.”

Berwick, a doctor with a background in pediatrics, also stays away from campaign trail food, waiting to eat until he gets home at night. His one regret is the lack of regular exercise: He likes to cross-country ski and bike in good weather.

“None of those fit into the campaign day very easily.”

Inside McKenna’s on a Thursday morning, he speaks in an even-keeled tone while eating a scrambled egg and several pieces of toast with strawberry jam. He’s happy with where he is in the five-way race to be the Democratic gubernatorial nominee, a field that is mostly left-leaning. The rest of the field includes Treasurer Steve Grossman, Attorney General Martha Coakley, former homeland security official Juliette Kayyem and former healthcare executive Joe Avellone, who is attempting to focus on moderate Democrats. Two independents are also running; all view presumptive Republican nominee Charlie Baker, making a second go for the Corner Office, as the main target for November.

The Democratic field’s left-leaning make-up is a reflection of the Massachusetts electorate, Berwick contends. Berwick, who briefly served as President Obama’s administrator for the Centers for Medicare and Medicaid Services in D.C., is arguably the most left-wing candidate among of his Democratic counterparts. He maintains that he is the only candidate opposing casinos, supporting Medicare for all at the state level and talking about tax distribution. And he touts his executive experience as the public watches state government grapple with embarrassing failings within the Department of Children and Families, with the state’s healthcare website, and the implementation of medical marijuana.

“When you think about how we’re going to reform corrections, or fight substance abuse in the commonwealth, or really get education to a universal platform of excellence, those agendas require strong leadership for innovation and improvement,” Berwick says. “That’s in my wheelhouse. That’s what I’ve done in my whole career. And other candidates can claim leadership experience but not at that level.”

Berwick founded the nonprofit Institute for Healthcare Improvement in the 1980s. He started with two employees, ended up with 125 employees and 300 associates and faculty members around the world. “That’s enough for a substantial bureaucracy to always be a threat,” he says. “The goal of leadership is to tear down walls, it’s to create the sense of a single team and to give the workforce the support they need to act like a team.”

He worked in a style similar to Mike Bloomberg, the billionaire mayor of New York, surrounded by his employees instead of being stuck inside a plush corner office. Ideas and conflicts were processed “in real time,” Berwick says. “You didn’t wait. You didn’t bake the cake and then hand it to someone, you cooked together.”

But much of the conflict on Beacon Hill happens between branches of government: It’s been the one constant, as governors and lawmakers come and go. The Democratic supermajorities in the House and Senate have their own executives to answer to: The House speaker and the Senate president.

Berwick says he would have an “open door policy” with lawmakers, and work, legislator by legislator, to put together a coalition of progressives. “You’re never the boss, you always have to recruit energies – and that’s my style – and be willing to fight when you have to fight,” he says. “I would like to manage government the way we’re managing a campaign. We have a grassroots campaign. We go out and build the support of the public. We do not have the access like the inside politicians do.”

When the Reporter notes that Gov. Deval Patrick attempted to rally the public and frequently clashed with legislative leaders early in his first term and it rarely worked out for the then-neophyte politician, Berwick says: “There has to be a multi-pronged approach here. And I do think public mobilization is key. But so is respect for the legislator. Nobody likes to be surprised.”

The public will be with him, he adds. “This is a public that is now readier than I ever would have thought for a new progressivism, and a sense that social justice and equity issues have got to become part of the central discourse,” he says. “And they’re not in Washington.” In the nation’s capital, there is more timidity around these issues than people in Massachusetts want, he argues.

“You can see in the national dialogue, you don’t hear a lot of the national leadership talking about justice and equity as foundational to public policy as it needs to be,” he says. “People back away from it. I don’t know why that is but that’s the case. And this public in Massachusetts doesn’t like it; they’re saying ‘no, there’s too much at stake.’”

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