When representatives of the national groups that support school tuition vouchers launched their campaign in Harrisburg earlier this year, they tried to appeal to Pennsylvania legislators' sense of moral outrage.

Why should low-income children be "trapped in failing schools?" Shouldn't they have the right to choose what school to attend, and get help with that school's tuition in the form of a state-funded voucher?

Invoking the imagery of an earlier generation's civil rights battles, advocates likened voucher opponents to the late Alabama Gov. George C. Wallace's blocking African American pupils by "standing in the schoolhouse door."

But more recently, the voucher bill became stalled in the state Senate, and FreedomWorks - the Washington-based group that is bankrolling voucher legislation efforts across the country - turned to tougher tactics.

The group deployed a campaign-style arsenal of negative "attack ads" aimed at legislative holdouts.

Now, FreedomWorks is naming names and taking aim at one of the state's two major teachers' unions.

FreedomWorks has scheduled a news conference on the Capitol steps to "expose" several Republican lawmakers whom it contends are "in the pockets" of the Pennsylvania State Education Association, which represents about 191,000 teachers and other public school employees.

In a news release, FreedomWorks said that at Wednesday's event, it would identify Republican lawmakers who have received between $1,000 and $6,000 in campaign contributions from the PSEA.

To be sure, those amounts pale in comparison with hundreds of thousands of dollars in donations from a pro-voucher organization, Students First PAC.

But the teachers' unions, long a powerful force in Pennsylvania's political campaigns, have made no secret of their opposition to the voucher bill. FreedomWorks officials say they are merely fighting back.

"The PSEA, along with other teachers' unions in Pennsylvania, have stepped up their game in opposition to this important bill, and it's time for us to respond," said David Spielman, campaigns coordinator for FreedomWorks. "You are either on the side of your neighbors, parents and children, or you are on the side of the unions. There is no fence to sit on."

- Amy Worden