Former Montana Lt. Gov. John Bohlinger (D) will run for his state's open Senate seat, creating a potentially competitive primary that could complicate Democrats' chances of holding onto the seat.

Bohlinger, a former Republican who served with former Montana Gov. Brian Schweitzer (D), has filed papers with the FEC to run as a Democrat.


His entrance into the race pits him against Montana Lt. Gov. John Walsh (D), who was recruited by national Democrats to run after other top-tier Democrats including Schweitzer passed on the race.

Sen. Jon Tester (D-Mont.) endorsed Walsh on Wednesday, calling the military veteran "a leader who puts service over self — who always puts Montana and Montanans first." 

Rep. Steve Daines (R-Mont.) is expected to announce his own bid later on Wednesday, and will likely begin the race with an edge in the GOP-leaning state.