THREE LAKES, Wis. — Gov. Scott Walker's re-election campaign says a small northern Wisconsin school district was aware of that a visit by the governor could lead to a campaign ad.

The Three Lakes School District voted to ban political activity Thursday after some staff members unknowingly showed up in a campaign ad for Walker. Board President Tom Rulseh says the board didn't know the governor's visit would lead to a campaign ad.

Walker campaign spokesman Brian Reisinger says Superintendent George Karling knew why the governor and a film crew were on school grounds. The campaign provided the Milwaukee Journal Sentinel with a permission form sent to Karling allowing the footage to be used for broadcast purposes.

The form features Walker's name on the letterhead and says the footage can be used for any broadcast purpose, but does not explicitly mention campaign ads.

Karling has apologized apologized for the ad.