As classes resume in Minneapolis and some other districts this week, Minnesota schools find themselves at ground zero of an intensifying debate that some see as a battle for the soul of public education.

Would-be reformers claim that the achievement gap between white and minority students in Minnesota reveals a broken system that can only be fixed by stripping the protections of seniority from teachers and holding them accountable for how their students perform on tests.

Public school defenders counter that real achievement will only come if the public gets serious about addressing the social and economic factors that put many disadvantaged students behind their classmates.

The debate has made Minnesota a focal point for national reform groups. It is one of about 10 states where reform groups have set up local operations most intensively in the past few years, said Patrick McGuinn, a Drew University professor who has written about the effects of education reform advocacy groups.

McGuinn said that the activity marks a shift of the education reform lobby from the federal level to the states.

"Their model is intensive investment in a small number of states where they think the reform agenda is going to be greeted most hospitably," he said. "They're more inclined to enter states where they think they can win the fight."

The efforts of all these groups have gotten the attention of school district leaders, and especially the teachers unions. In Minneapolis, some teachers have escalated their rhetoric against what they call corporate reform of education.

"I've been trying to push back for a long time and I think that other people are catching on," said Rob Panning-Miller, a teacher and former Minneapolis union president.

Minnesota has had homegrown reform efforts for decades. The nation's first charter school opened in St. Paul 21 years ago. Educator Joe Nathan's Center for School Change in St. Paul has been pursuing changes in public schooling since 1989. The Minneapolis, St. Paul and Mc­Knight foundations, and those associated with Medtronic and General Mills, have funded reform efforts.

And in recent months, many Minneapolis parents have received postcard messages making a hardball claim: The city's school district, they contend, spends too much on students and gets too few results.

The mailing is from a Chaska-based group called Better Ed, one of the more strident voices in a rising chorus of advocacy groups vowing to set public schools straight.

Better Ed's campaign so far appears to consist of the postcards sent out during the last legislative session and a website. The site says little about who is behind the organization's efforts, describing itself as an offshoot of Intellectual Takeout. That nonprofit has a $1.6 million budget and is headed by a figure once linked to a local conservative think tank and the Republican Party. Better Ed declined a request for an interview last week.

While Better Ed is a local operation, many of the most active advocacy groups originated outside the state.

StudentsFirst, for example, was formed in 2010 and operates in 18 states. It opened a Minnesota office in 2012, reportedly at the invitation of legislators and business interests. Its state director is former Washington County legislator Kathy Saltzman.

Educators for Excellence formally launched just this month. The Minnesota office is only the third affiliate of a New York-based advocacy group that asserts it is inserting the voice of teachers into education policy, a role ­historically played by teacher unions. Its state director, Madaline ­Edison, is a Teach For America alum and the group boasts a membership of 320 teachers.

Teach For America itself, which recruits college graduates for high-poverty schools, entered the Twin Cities in 2009. It has a current Twin Cities budget of $2.7 million and 12 staffers. Its reform agenda focuses on urging people who complete a two-year teaching stint to get involved in school improvement. Josh Reimnitz did that in Minneapolis, winning election to the school board last fall, defeating a union-backed candidate.

Ciresi is a big local player

A national group with significant local support is New York City-based 50 CAN (Campaign for Achievement Now). Minnesota is its third state and high-profile attorney Michael Ciresi sits on its board of directors. The local office opened in 2011 and immediately declared a "state of emergency" for Minnesota schools. Its agenda overlaps with StudentsFirst in several areas. MinnCAN and StudentsFirst both advocate for quality prekindergarten programs, evaluating teachers and principals, and tying layoff decisions to teacher performance. StudentsFirst also lobbies for greater school choice for low-income families.

An increasingly important local funder of reform efforts is the Robins, Kaplan, Miller & Ciresi Foundation for Children. In the past three years it has sent more than $600,000 to groups that advocate school reform, and a slightly larger sum to fund charter schools and other alternatives to traditional district education.

Ciresi, the foundation's president, also put his own money into the Minneapolis school board election. Ciresi and his wife, Ann, gave $2,600 to support Reimnitz, by far the biggest household contribution in the race. They gave $2,000 of that through a political fund associated with the parent organization for MinnCAN. Reimnitz set a school board campaign spending record of almost $39,000.

Ciresi said his support for Reimnitz "wasn't an ideological thing. It was how do we support candidates who have an independent voice," he said.

He pointed out that his foundation also has supported the Minneapolis and St. Paul districts for campaigns to raise property taxes, and gave a $200,000 grant to Minneapolis that funded a 2009 study of changing layoff practices and evaluating teachers.

Minnesota's climate for sweeping school reform has cooled with the election of a DFL governor in 2010 and DFL control of the Legislature in 2012. But with teacher contracts being negotiated statewide, the school reform agenda will likely remain a hot topic.

Steve Brandt • 612-673-4438