MADISON, Wis. (AP) -- Gov. Scott Walker's campaign and the Wisconsin Republican Party are suing the state elections board, saying its process for reviewing recall petitions is unconstitutional.

The lawsuit was filed Thursday in Waukesha County circuit court. It asks a judge to order that the Government Accountability Board look for and eliminate duplicative signatures, obviously fake names such as Mickey Mouse, and signatures with clearly illegible signatures.

The lawsuit says allowing multiple signatures violates the U.S. constitution's equal protection clause.

But the board says state law places the burden of challenging those signatures on the office holder being targeted for recall.

Board director Kevin Kennedy defended the review process, saying it has been used since the 1980s in every state and local recall effort against incumbents from both political parties.