Minnesota Gov. Mark Dayton on Wednesday said he would appoint Lt. Gov. Tina Smith to fill the Senate seat being vacated by outgoing Sen. Al Franken, who has yet to announce his resignation date.

Smith said Wednesday she will run for the remainder of Franken’s term, which is up in 2020. The special election will be held concurrently with next year’s midterms, when Democratic-Farmer-Labor Sen. Amy Klobuchar also faces voters.

“I shouldn’t be underestimated, and if I weren’t confident, I wouldn’t be doing this,” Smith said.

Smith said Franken’s staff is “working to finalize the details” of his resignation, but she expects the transition to occur in early January. She’s meeting with his staff in Minnesota Wednesday and hopes most of them will stay on board.

Asked if Dayton had anything in writing from Franken about his resignation, the governor said no. “I know Sen. Franken is a man of his word,” he said. “I fully expect he will follow through.”