Democratic Senator John Walsh announced today that he is dropping his bid for reelection in Montana amid allegations that he plagiarised a significant portion of his master's thesis at Army War College. The school is set to begin an investigation into the charges next week. In his announcement, Walsh said that accusations of plagiarism have "become a distraction."

"I am ending my campaign so that I can focus on fulfilling the responsibility entrusted to me as your U.S. Senator," Walsh said today. "You deserve someone who will always fight for Montana, and I will."

Walsh, who was appointed to his position in February after Senator Max Baucus' was named the U.S. ambassador to China, also announced that he intends to finish out his term (ending in January of 2015).

With Walsh out, Politico notes, Democrats in Montana are facing a tough race to keep the Senate seat Baucus held since 1978:

Pressure is building in Democratic political circles for Nancy Keenan, a long-time abortion rights activist, to jump into the race, even though sources say she has so far resisted. And at least one other Montana Democrat, former lieutenant governor John Bohlinger, has expressed interest.

Whoever does step in would face Republican Rep. Steve Daines, who is heavily favored to win a seat the GOP has not held since 1913.

Montana Democrats have until Aug. 20 to get a new candidate on the ballot.

[Image via AP]