Democratic U.S. Sen. Al Franken of Minnesota announced today that he will resign his Senate seat “in the coming weeks” in the wake of multiple allegations of inappropriate sexual behavior toward women that ranged from unwanted advances to groping. The incidents occurred over a number of years dating back to before he was elected to the Senate. The first allegations came to light three weeks ago and came to a head yesterday when several of his female colleagues called on him to resign. At least 28 of the Senate's 48 Democrats have said that Franken should step down.

Under Minnesota law, Democratic Gov. Mark Dayton will appoint a replacement who will fill the seat until a special election is held in November of 2018. While Dayton could appoint a "statesman caretaker," someone of political prominence who would keep the seat warm until the special election, national Democrats are likely to prefer an appointee who will run in the special and use the 11 months between now and then to build a campaign that will have all the advantages of incumbency. This means that Minnesota will have two Senate races on the ballot next year as U.S. Sen. Amy Klobuchar is up for re-election.

Franken won this seat in 2008, defeating GOP incumbent Norm Coleman by just 312 votes. The recount and legal battles went on for six months, and Franken wasn't sworn in until July 7, 2009. He was re-elected to a second term in 2014 with 53 percent of the vote, defeating businessman Mike McFadden.

While there is a presumption that Republicans aren't competitive statewide in Minnesota, Franken's close 2008 race and Democratic presidential nominee Hillary Clinton's narrow 43,695-vote victory in 2016 would suggest otherwise.

Who Dayton might appoint is anyone's guess and he has no shortage of options. Lt. Gov. Tina Smith is probably high on his list. In addition, the five Democrats in the House delegation make the list: U.S. Reps. Tim Walz, Betty McCollum, Keith Ellison, Colin Peterson and Rick Nolan. Walz has announced he is running for Governor next year, but he might be persuaded to accept an appointment and switch races. And speaking of the gubernatorial contest, it is an open seat and both sides are looking at crowded primaries; there are already six announced Democrats. It is possible that Dayton might look here for an appointee. Apart from Walz, St. Paul Mayor Chris Coleman, st. Auditor Rebecca Otto, and state House Minority Leader probably make the cut. Attorney General Lori Swanson is likely on the list as well.

Republicans will keep their powder dry until Dayton makes the appointment. Former Gov. Tim Pawlenty is probably the highest profile potential candidate. McFadden, Franken's 2014 opponent, might look at the race. The three Republicans in the congressional delegation — U.S. Reps. Jason Lewis, Erik Paulsen and Tom Emmer — will certainly take a look at running. Among the announced and potential gubernatorial candidates, former state party chair Keith Downey, Hennepin County Commissioner Jeff Johnson and state House Speaker Kurt Dault might find the prospect of a Senate race more appealing than a crowded gubernatorial primary. Norm Coleman, the incumbent Franken defeated in 2008, has also been mentioned as a potential candidate. There are likely other Republican names that will find their way onto the list over the coming weeks.

At this writing, the situation is very fluid and is likely to take weeks to sort itself out. The race will go into the Toss Up column during this process. The rating will be reassessed as the landscape gains some clarity.