Around the time school started this fall, teachers across Minnesota found their mailboxes filling up with postcards printed on glossy paper.

One featured a smiling teacher, clutching a stack of papers in front of a classroom, and a question: "Is what's best for the union really what's best for you and your classroom?"

"Minnesota teachers now have a choice," read another. "Get the facts. Do what's best for YOU."

The state's public school teachers find themselves at the center of a divisive battle over the future of their labor union, Education Minnesota. In late June, the U.S. Supreme Court ruled that public employees who do not join unions cannot be required to pay for collective bargaining.

Since then, the leaders of Education Minnesota — one of the state's most powerful political forces, with 90,000 members and formidable campaign spending power — have been pushing hard to keep the numbers up.

Meanwhile, outside groups hoping to diminish the union's size and influence have seized on the moment, launching a well-funded campaign to get teachers to reconsider their membership.

The debate hit a fever pitch last week, during Education Minnesota's annual seven-day "drop" period — the only time of year in which members can opt out of the union. That window closes Sunday.

Both sides are seeking greater influence on some of the biggest and most controversial issues in education, including teacher tenure rules and curriculum policy.

Education Minnesota President Denise Specht said she thinks the efforts by groups like the Center of the American Experiment and Americans for Prosperity, both conservative advocacy organizations, have mostly irritated her union's members — not persuaded them to tear up their union cards.

"A lot of these [mailings], quite honestly, have ended up in the trash," she said. "They look like junk mail. Our members are insulted by it; they don't like what they're trying to do."

But Kim Crockett, vice president and senior policy fellow at the Golden Valley-based Center of the American Experiment, said her group's efforts are making a difference in informing union members about a court decision she sees as "pro-freedom, pro-First Amendment."

"Our job is to let teachers know what their rights are," she said. "We really respect teachers and want them to make the decision that's right for them."

Website and billboards

To that end, Crockett's group launched a website called Educated Teachers, which includes information about the Supreme Court's ruling in Janus vs. AFSCME — a decision that affected so-called "fair share" public employees, who were not union members but instead paid a reduced annual fee to help cover the cost of bargaining. Before the ruling, Education Minnesota had about 5,000 members in that category, plus about 86,000 active members paying full dues. Adding in students and retirees, the union's membership was close to 90,000.

The website points teachers to companies offering professional liability coverage — something they'd lose if they opt out of union membership — and prominently features a form letter that union members can fill out to cancel their membership with Education Minnesota.

The Center of the American Experiment has also funded billboards lauding the court's ruling as "Teachers' Independence Day" and has solicited union members interested in filing lawsuits against their unions over the payment of dues or the procedures around dropping out of the union. Crockett said her group has heard from and is working with a number of teachers who are dissatisfied with how Education Minnesota represents them, and who are unhappy with the candidates and policies the group lobbies for at the state and federal levels.

She said many of the teachers with misgivings about union membership fall on the conservative end of the political spectrum and are unhappy with Education Minnesota's strong backing of Democratic candidates and policies. (This year, Education Minnesota's political action committee has contributed more than $1.2 million in campaign cash toward state elections, almost entirely to DFL candidates and organizations.)

But Crockett said most of those teachers are unwilling to speak publicly about their concerns, fearing reprisal from co-workers and union leaders.

Membership impact unclear

Linda Hoekman, a physics teacher at Champlin Park High School, is one of a few teachers who have been outspoken about their support for the court ruling. She's featured on the Educated Teachers website and has a pending lawsuit against Education Minnesota over the "fair share" fees she paid as a nonunion member. Hoekman said she believes the union too often lines up on the side of school administrators' policy preferences, rather than listening to teachers.

"I want to be free to voice a different opinion, to propose different changes and have encouragement available," she said.

It's unclear how many teachers agree with Hoekman — and it may be unclear for some time. Specht said Education Minnesota does not plan to disclose its membership numbers after the "drop" window closes Sunday.

The union is required to file paperwork with the federal government this fall that includes membership numbers, but that information won't be public until next spring and will only include statistics through the end of August. That means Education Minnesota membership data for this month won't be available until spring 2020, unless the union releases it before then.

Some teachers echoed Specht's prediction that the group's membership won't see much of a dip.

Ann Hersman, president of the Minnetonka Teachers Association, said she and other teachers in her district have been getting multiple postcards every day for weeks. She said several union members were immediately skeptical of the mailings and of their senders' intent. Hersman said she's turned it into a contest: she'll buy doughnuts for whichever school building's teachers collect the most postcards.

"It kind of warms my heart that teachers aren't falling for it," she said of the mail campaign. "They get it, that this is not what's best for our profession."

Allison Sirovy, a middle school language arts teacher in the Osseo school district, said the outside groups' efforts have had the opposite of their intended effect on her and other teachers at her school. She said she used to "take the union for granted," but now she's feeling inspired to get more involved.

She said the pitch in the mailings telling teachers they should spend the approximately $1,000 they put toward union dues each year on something else is falling flat, and that she's convinced it's money well spent to help give her a voice about her workplace.

"We know [the union] is not perfect, and there are always things that can be improved," she said. "But I feel in the long run that the union looks out for teachers and really looks out for the kids."

Erin Golden • 612-673-4790