[14][15] Walsh received a Master's degree in strategic studies from the United States Army War College in 2007.

[22] Former governor Brian Schweitzer wrote a letter to the board in support of Walsh, who claimed the plagiarism was unintentional and that he had been on medication for PTSD at the time.

On August 22, the board found that Walsh's plagiarism was "egregious" and "intentional" and that the paper was "primarily composed of verbatim liftings from other sources".

[26] He resigned in 2012 to run for Lieutenant Governor, and continued to serve as a traditional Army Guardsman (one weekend drill per month, two weeks of annual training each year).

[28] A 2010 Army Inspector General report concluded that Walsh used the Adjutant General's post for "private gain" by pressuring subordinates into joining the National Guard Association of the United States in an effort to bolster Montana's membership numbers and enhance Walsh's candidacy for Vice President of NGAUS.

[24] Walsh disputed the IG's report, explaining that it stemmed from a disagreement in interpreting the rules which govern when and how Department of Defense employees can take part in activities such as running for a NGAUS leadership position.

"[30] Contemporary news accounts indicated that Schweitzer wrote to Chiarelli to state his confidence in Walsh's integrity and abilities, and to urge his promotion to the federally recognized general officer ranks.

[32] In March 2012, Attorney General and presumptive Democratic gubernatorial nominee Steve Bullock selected Walsh to be his running mate.

In the general election, Bullock and Walsh defeated their Republican opponents, former Congressman Rick Hill and his running mate, State Senator Jon Sonju, by 49% to 47%.

[41] Along with six other Democratic senators, Walsh co-sponsored the Small Business Tax Credits Accessibility Act, which was introduced in the House of Representatives on February 28.

[45] He asked Congress to support the Keystone Pipeline and proposed to leave infrastructure decisions to the State Department, instead of the President.

He spoke briefly about his experiences as an infantry officer there, and urged other Congressmen to consider the ongoing impacts of war in their decision.

[54] Rancher Dirk Adams and former Montana Lieutenant Governor John Bohlinger also ran for the Democratic nomination.

[63] The Missoulian, the Billings Gazette, and the Bozeman-area Montana Pioneer published editorials calling for Walsh to end his candidacy.

[6][68] In October 2014, the National Republican Senatorial Committee revealed that a researcher on its staff had found the plagiarism and leaked it to The New York Times.