"I am ending my campaign so that I can focus on fulfilling the responsibility entrusted to me as your U.S. senator," Walsh said. "You deserve someone who will always fight for Montana, and I will."
Walsh's decision follows a report in The New York Times in July which said that Walsh plagiarized significant parts of his master's thesis.
Since then Walsh had reportedly been trying to decide whether to continue running in the race or not. Even before the plagiarism story broke Walsh had an uphill battle to victory and faced a formidable challenge in Rep. Steve Daines, the Republican nominee for U.S. Senate.
According to National Journal, Walsh announced his decision to drop out in a call with staffers. His wife was "openly sobbing" while she thanked members of Walsh's campaign, National Journal said.
Walsh had until Monday to withdraw from the race. Because of Walsh's decision to drop out, the Montana Democratic Party now has until Aug. 20 to pick a new candidate to run for Senate.
Read Walsh's full announcement to supporters below:
Nothing is more important to me than serving the people of Montana. It’s been my privilege for more than 30 years, defending both our state and nation.
The 2007 research paper from my time at the U.S. Army War College has become a distraction from the debate you expect and deserve. I am ending my campaign so that I can focus on fulfilling the responsibility entrusted to me as your U.S. Senator. You deserve someone who will always fight for Montana, and I will.
I am proud that with your support, we held our opponent accountable for his hurtful record to privatize Medicare, to deny women the freedom to make their own health decisions and to sell off our public lands. I know how important it is to continue the fight for these Montana values, and it is time for us all to return to the real issues of this election.
I am grateful for the opportunity to have met countless people in the course of this campaign who have offered support – who know what’s at stake for the future of our great nation. That is why public service is so important to me, and why I look forward to continuing to fight for Montana in the U.S. Senate.
This post was updated.