Karla Bigham, elected in a special election Monday to the Minnesota Senate, said Tuesday that she will resign her Washington County board seat on Feb. 20. That’s the day that the legislative session begins.

Bigham, 38, chairs the five-commissioner board and represents Cottage Grove and surrounding cities and townships. Her current term expires in November.

The remaining four board members are expected on Feb. 20 to approve a public hearing to consider possible appointees to fill her District 4 seat until the November election. District residents interested in being considered for the appointment should send a letter to County Administrator Molly O’Rourke by March 7.

Bigham, a DFLer, was elected to the County Board in November 2014, defeating incumbent Autumn Lehrke. She also has served on the Cottage Grove City Council and in the Minnesota House of Representatives.

On Monday she bested GOP candidate Denny McNamara in the race to represent a southeast metro district that has historically elected Democrats. The seat opened up in November after incumbent DFL Sen. Dan Schoen, of St. Paul Park, announced his resignation following accusations of sexual misconduct.

Bigham has been a notable critic of unfunded mandates — expenses imposed on counties to pay for state programs — and said she will take that battle to the Legislature.

“We’re going to get the unfunded mandates under control,” she told fellow commissioners on Tuesday. “I hope you could see me as an extension of the County Board up there [at the Legislature] because we have a lot of work to do.”