Choices for the Legislature

THE BOSTON GLOBE makes the following endorsements in three competitive Democratic primary races Tuesday:

The 2nd Suffolk District in the Senate contains some of Boston's toniest real estate along with some of the city's most troubled neighborhoods. The Globe endorses challenger Sonia Chang-Diaz as the better candidate to represent the diverse district, which stretches from the Back Bay and Beacon Hill to Roxbury, Dorchester, and Jamaica Plain.

Chang-Diaz has demonstrated solid knowledge of the issues facing the district. She opposes giving public funds to the controversial Columbus Center real estate development. As a former public school teacher, she understands that families in the 2nd Suffolk and elsewhere are starved for better educational opportunities. And as a former aide to state Senator Cheryl Jacques, Chang-Diaz would come into office with more legislative experience than most first-term lawmakers.

Incumbents can always claim experience as an advantage. Since taking office in 1993, incumbent Dianne Wilkerson has been a passionate advocate for her district's interests and has delivered for poor and minority communities. But her handling of her own legal affairs has been disastrous. Last month, she reached a settlement with the attorney general's office in which she admitted to violations of campaign-finance laws and agreed to a stiff $10,000 fine.

Wilkerson and Chang-Diaz agree on most of the issues. Chang-Diaz puts the matter succinctly: Why should voters in the 2nd Suffolk have to choose between solid policy positions and a commitment to ethics and accountability? They shouldn't.

In the Senate's 4th Middlesex District, two capable Democrats are vying in the primary to succeed James Marzilli of Arlington, who is not seeking reelection amid legal and mental health problems. Our endorsement goes to former Lexington firefighter and official of the Professional Fire Fighters Association Kenneth J. Donnelly of Arlington. Donnelly has staked out progressive positions on education, the environment, social issues, and healthcare, and would bring to public-employee issues more than 20 years of experience, going back to the pension reform efforts of 1987.

Donnelly sees improved education as the state's highest priority, citing the achievement gap between students from towns where more than 90 percent attend college and cities like Holyoke, where just 12 percent do. He favors longer school days and school years, expanded preschool education, and better training for students not going to four-year colleges. How to pay for this? Donnelly would not shrink from going after corporate-tax loopholes. He understands that making big ideas viable requires a solid revenue base.

He favors a single-payer healthcare system but wants to see the state's health reform plan get the funding it needs. He called "absolutely crazy" the modest $295 a-year fee that companies without widespread coverage are required to contribute for each uninsured worker.

Donnelly's primary opponent, Arlington Selectman Jack Hurd, has not shown the same growth beyond local concerns.

This district includes Arlington, Billerica, Burlington, and parts of Lexington and Woburn. Donnelly would give its voters solid, experienced representation.

The 6th Middlesex District lies entirely in Framingham - a town of 65,000 with challenges that require thoughtful representation in the State House on many issues, including commercial development, environmental health, education funding, and services to the elderly and immigrants. In a strong, three-candidate field for state representative, challenger Dawn Harkness stands apart for her energy and versatility. The Globe endorses her bid.

Harkness, an attorney who drives a green ambulance that runs on waste vegetable oil, can appear unorthodox at times. But the Framingham Town Meeting member has taken a traditional route in politics, serving with distinction on several town boards. Her efforts on behalf of the town's Greener Framingham Committee could help her play a statewide role in helping to attract alternative-energy companies to the state. And her grasp of fiscal issues is firm, as displayed this week at a candidate forum, where she made a measured case for casinos as a means to increase state revenues for education and property tax relief. Harkness is also an unapologetic supporter of public charter schools, which are driving school reform in Massachusetts.

Pam Richardson, the one-term incumbent, has been a consistent voice for public education funding. Challenger Chris Walsh is an architect with strong ideas about redeveloping downtown Framingham. But it is Harkness who would serve in the tradition of Deborah Blumer, the district's independent-minded, straight-talking state rep who died in 2006.