Montana Gov. Steve Bullock (D) appointed Lt. Governor John Walsh (D) Friday to take the place of Sen. Max Baucus (D-Mont.), who the Senate confirmed Thursday to be United States Ambassador to China.
Walsh will have to run for reelection in 2014 for a full six-year term. He has already begun campaigning for the seat.
According to a November Public Policy Polling survey, he has a slight lead over former Lt. Governor John Bohlinger, who switched parties to run in the Democratic primary. However, the poll found that he trails leading GOP candidate Rep. Steve Daines (R-Mont.) by a 52-35 margin.
Montana is a crucial for Democrats' hopes of keeping control of the United States Senate. Though the state reliably votes for Republicans in presidential elections, its two senators are Democrats.
Republicans are hoping that partisan gravity catches up with the state, though that did not happen in 2012, when Sen. Jon Tester (D-Mont.) won reelection.
Montana's primary is on June 3, and the general election will be held on November 4.