The 14 Wisconsin state Senate Democrats who left the state two weeks ago will now face fines of $100 for each day they miss, if they miss two or more days.
Republicans remaining in the Senate approved the daily fine on Wednesday morning with none of the Democrats present.
The Democrats left Wisconsin in order to delay indefinitely a Republican-backed bill taking away collective bargaining rights from public employees.
The resolution passed on Wednesday also requires the missing Democrats to reimburse the Senate for any costs incurred during attempts to force them to return. Their salary and other per diem payments can be withheld until they pay back the penalties and costs.