Advocates of private school vouchers often point to Wisconsin as a model. The state has had a voucher plan since the early 1990s. At first limited to secular private schools in the city of Milwaukee, the voucher scheme was later expanded to include religious institutions.

Other changes are more recent. A similar plan was set up in Racine, and in Milwaukee, income caps were raised, and suburban private schools were brought into the plan. The upshot of this is that a plan that was once described as an “experiment” to help low-income families in troubled areas of Milwaukee is now firmly entrenched and aiding middle-class families in the suburbs.

Who saw that coming?

Well, actually, Americans United did. Twenty-one years ago when the Wisconsin plan was proposed, we warned that it wouldn’t increase student performance, wouldn’t help the poor and would end up bailing out financially troubled religious schools.

No, we’re not psychic. Plain old common sense told us that the claims of voucher boosters were wildly exaggerated. On student performance, for example, the record is clear: Voucher students are doing no better than their public school counterparts, and in some cases are doing worse.

Amazingly, this is happening even though the playing field is uneven. Voucher schools, unlike public institutions, don’t have to accept all comers. Voucher schools have the ability to cream the best students – and they still can’t out-perform public schools.

At the same time, many of the private schools taking part in the program see imparting religious instruction as their primary goal.

In Milwaukee, Salem Evangelical Lutheran School was on the verge of closing due to low enrollment when, lo and behold, a miraculous infusion of taxpayer money gave the school new life.

“This is an outreach,” Principal Steven Carlovsky told the Milwaukee Journal Sentinel. “We’re bringing the Gospel.”

Indeed the school is – thanks to a government bailout funded by a lot of people who are not evangelical Lutherans and who may disagree with the gospel Carlovsky’s school promotes.

Wisconsin, under its Tea Party-friendly governor Scott Walker, is going through a rough patch right now. But all hope is not lost. In a recent primary election, the pro-voucher front group the American Federation for Children, founded by billionaire Betsy DeVos of Amway fame, poured money into a race for state assembly between incumbent Jason Fields and challenger Mandela Barnes.

Vouchers were a major issue in the campaign. Fields, a voucher advocate, relied on DeVos’ money and a barrage of radio ads. By contrast, Barnes ran a grassroots campaign and knocked on a lot of doors in the district. He engaged Fields directly on the voucher issue and stressed his support for public education. Barnes won in a blowout, taking 68 percent of the vote.

The results should give Wisconsin’s leaders pause. Americans want a strong, adequately funded public school system, not privatization. Wisconsin’s voucher plan was a mistake 21 years ago, and it remains a mistake today. The “experiment” has failed. It’s time to end it.