For GOP's Baker, a long resume at a relatively young age

For as long as d’Arbeloff can remember, Baker is the guy who has explained complex policies to her with simple diagrams on scraps of paper. He is also the avid music fan who occasionally worked as a bouncer at rock shows in his youth and remains unabashed about taking his teenagers to see the Dropkick Murphys.

As a new candidate for governor, Baker, now 52, is unknown to many voters, and he is not without critics on policy. Some service providers used the term ‘‘slash and burn’’ to describe his 1990s efforts, as undersecretary for health and human services, to close state hospitals and rein in costs. But Baker has earned respect on Beacon Hill and in the business community as a smart, measured leader.

‘‘He’s easygoing, but no one should mistake that [he also has] a steely determination to get the right result,’’ said Paul Cellucci, the former lieutenant governor and governor who worked with Baker for much of the 1990s.

Baker grew up in Needham — aside from a stint in Washington, while his father served as a deputy undersecretary of transportation in the Nixon administration — and attended Needham High, where he was a multisport athlete.

The oldest of three boys born to a Republican father and Democrat mother, Baker was a voracious childhood reader and early participant in kitchen-table debates that ran ‘‘hot, heavy, and all the time,’’ said his father, Charles Sr., who also served in the Reagan administration and is now retired from business, government, and education.

‘‘He’s got a great degree of curiosity,’’ Baker’s father said. ‘‘He’s a quick study, but he’s a really serious thinker. A lot of quick studies, they stop right there.’’

At Harvard, Baker concentrated in English, lettered in basketball, and began a Big Brother relationship that he maintained through decades, eventually serving as best man at his Little Brother’s wedding. After earning an MBA at Northwestern’s Kellogg School, where he met his wife, Lauren, Baker worked as a consultant and helped build the Pioneer Institute, a Boston think tank with a libertarian bent.

Baker’s ‘‘best quality is probably his ability to get along with people. And second, he has an excellent mind, and he knows how to channel energy,’’ said Lovett C. Peters, the retired oil man who founded Pioneer, made Baker his second hire, and remains an office regular at age 96.

Peters ultimately recommended Baker to William F. Weld, who consulted Baker broadly on policy issues and asked him to be undersecretary for the Health and Human Services Department after his 1990 election.

But first, Weld arranged for Baker to speak with David P. Forsberg, Weld’s choice for secretary of the agency, to ensure they had chemistry. The resulting conversation was a dizzying call in which Baker peppered Forsberg with questions and wowed him with ideas that would help shape the administration’s plan to cut costs and reorganize public services.

Afterward, Forsberg told his wife, ‘‘I think I’ve just been interviewed to see if I can be somebody’s boss,’’ he recalled yesterday.

By the time Weld left office, Baker had joined his Cabinet, serving first as health and human services secretary and then as secretary for administration and finance, a position he continued under Cellucci. But Baker passed at the opportunity to run as Cellucci’s lieutenant governor, a spot subsequently offered to Jane Swift.

Baker instead left government to become chief executive of Harvard Vanguard Medical Associates, a nonprofit group practice with physicians across Eastern Massachusetts. A year later, in mid-1999, the struggling HMO Harvard Pilgrim Health Care brought Baker in to right an organization that was hemorrhaging money.

After initial bumps, Baker oversaw a turnaround that included more than two dozen consecutive profitable quarters, at the same time the company finished atop the National Committee for Quality Assurance’s ranking of health plans five years in a row.

Even as he ran Harvard Vanguard, served as selectman, kept a healthcare blog, and maintained a steady presence at his children’s sporting events, friends say, Baker nurtured an interest in becoming governor.

‘‘There are still idealistic people in this business who care and think they can help, and that’s why they get in,’’ said Buckingham, now director of public affairs for Pfizer Inc. ‘‘He’s one of them.’’

Steve Rosenberg of the Globe staff contributed to this report.