Wis. Stat. § 13.05
Any member of the legislature who gives, offers or promises to give his or her vote or influence in favor of or against any measure or proposition pending or proposed to be introduced in the legislature in consideration or upon condition that any other person elected to the same legislature will give or will promise or agree to give his or her vote or influence in favor of or against any other measure or proposition pending or proposed to be introduced in such legislature, or who gives, offers or promises to give his or her vote or influence for or against any measure on condition that any other member will give his or her vote or influence in favor of any change in any other bill pending or proposed to be introduced in the legislature, is guilty of a Class I felony.
Wis. Stat. § 13.05