Democrats have been scrambling to find a candidate since Senator Max Baucus announced earlier this year he was retiring at the end this term.
Now, they have a forerunner in Lt. Gov. John Walsh, while Republicans expect U.S. Rep. Steve Daines to declare candidacy, raising the profile of Montana's race for the Senate.
The Montana contest winner could help decide whether Democrats maintain their current 55-45 majority in the U.S. Senate.
Lt. Gov. Walsh is joined by political unknown Dirk Adams of Wilsall on the Democratic ticket.
Former Lt. Gov. John Bohlinger - a former Republican - has also said he is considering a run as a Democrat.
The Montana Democratic Party said they won't make official comments preceding the November election, but Montana GOP officials said they see a great opportunity to pick up a seat held by Senator Baucus for 35 years.
Bowen Greenwood, Executive Director of the Montana Republican Party, said, "This is their sixth or seventh attempt at a recruit for this race, and multiple top Democrats have passed, and I guess I'm glad for them that they finally found someone to run."
Many Republicans expect U.S. Rep. Steve Daines to enter the race and be their front-runner.
Already in the running for Republicans is Kalispell resident, David Leaser, an air traffic manager at Glacier Park International Airport.
Republican State Senator Matthew Rosendale has said he will run for office in 2014, but has yet to choose the Senate or the House.
Republican Corey Stapleton and State Representative Champ Edmunds also had intentions to run for Senate, but later announced candidacy for the U.S. House.
Several big name Democrats declined to run for the Senate seat, including former Governor, Brian Schweitzer.
Candidates can officially file for candidacy with the Secretary of State on January 9, and the election takes place November 4.