Are you in a union or other contract? That might change my answer.
Generally employees in Wisconsin are "employees at will" which means that they have no contract with the employer and the employee and employer both can terminate the relationship at will. Thus, a change in hours, responsibilities, etc. are permissible and you can decide whether to continue the work relationship or terminate and find another job. The employer could also decide that they do not want to retain you and find somebody else for the job for any reason. Of course, this does not mean the employer can discriminate in the hiring or firing process (age, sex, religious, etc. discrmination) but otherwise is free to exercise its discretion about whether to hire, keep on or change positions for an employee.
This is not legal advice, but general information related to the topic since I do not know all of the facts of the situation and you have not retained me as your attorney. To get exact legal advice please contact and retain an attorney of your choosing.