Wis. Stat. § 11.1202: Earmarking.

(1) The treasurer of a candidate committee may agree with a prospective contributor that a contribution is received to be used for a specific purpose not prohibited by law. That purpose may not include a disbursement to a committee to support or oppose another candidate.

(2) When a contribution is made to a committee other than a candidate committee, the contributor may not direct the committee to make a disbursement to a committee to support or oppose another candidate.

(3) Except for transfers of membership-related moneys between committees of the same political party, no committee may transfer to another committee the earmarked contributions of others. Transfers of membership-related moneys between political parties shall be treated in the same manner as other transfers.