MADISON, Wis. (AP) -- All four Republican state senators targeted for recall have filed challenges to signatures collection on petitions.

It is now up to the Government Accountability Board to determine how many of the signatures should be counted and how many should be invalidated. The board's deadline for reaching its decision is March 19.

The four targeted senators are Majority Leader Scott Fitzgerald of Juneau, Pam Galloway of Wausau, Terry Moulton of Chippewa Falls and Van Wanggaard of Racine.

Fitzgerald said in a release he was alleging that more than 4,300 signatures were invalid. That is more than enough to stop any election.

It wasn't immediately known how many signatures each of the other three challenged.

Republicans hold a 17-16 majority in the Senate.