ST. PAUL (AP) -- Sen. Al Franken's time in the U.S. Senate is coming to a close.

Franken's resignation was expected to be made official Tuesday. It comes nearly a month after he announced his plans to leave Congress after a swirl of sexual misconduct allegations that began in November.

The timing of the Democrat's official resignation was unclear. But it sets the stage for current Minnesota Lt. Gov. Tina Smith to be sworn in Wednesday morning.

Governor Mark Dayton picked his second-in-command last month to replace Franken. She plans to run for the seat in a November special election.

Franken joined the Senate in 2009 after winning in a months-long recount. He held an event in Minneapolis last week to thank supporters and friends.