ST. PAUL, Minn. (AP) — U.S. Sen. Al Franken's potential resignation is setting off a rush to find a possible replacement.

The responsibility to replace the Minnesota Democrat would fall to Democratic Gov. Mark Dayton. Dayton must decide whether to appoint a temporary placeholder or try to set someone up for a 2018 special election to finish out Franken's term, which runs through 2020.

Lt. Gov. Tina Smith is near the top of any list, having served as Dayton's second-in-command for three years. Smith is a longtime political operative who ran several campaigns and previously mulled a run for governor. Dayton could also look to Attorney General Lori Swanson or State Auditor Rebecca Otto.

Dayton's office declined to comment. Franken's office said he will make an announcement Thursday in a speech on the Senate floor.