ST. PAUL (AP) -- Minnesota Gov. Mark Dayton has appointed Lt. Gov. Tina Smith to fill Sen. Al Franken's seat until the November election.

Dayton's announcement Wednesday had been widely expected. Smith served as Dayton's trusted chief of staff for three years before ascending to become his No. 2.

She was once considered a likely candidate to succeed him, but had announced in the spring that she wouldn't run for governor. However, she is expected to run in the November special election to complete Franken's term through 2020. Dayton had come under intense pressure from top Democrats in Washington to appoint someone who wouldn't merely serve as a seat-warmer.

Franken announced last week he would resign over allegations of improper behavior from several women. He hasn't yet set a date to leave Congress.