The head of the Democratic Senatorial Campaign Committee said the party "absolutely" stands by Sen.
"Stacked up against his record in Iraq, his record in the National Guard, his service in Montana, I think the voters will understand that full picture," Sen.
The New York Times reported Wednesday that Walsh had failed to attribute sections of the 14-page paper that he submitted to earn a master's degree from the
Walsh's 33-year military career has been a primary selling point for the political novice as he seeks to win election for a full term in November; he was appointed this year to replace
Walsh first told the New York Times that he did not believe he had done anything wrong. In a subsequent interview after the Times report was posted online, Walsh told the Associated Press he had suffered from post-traumatic stress disorder after his service in Iraq.
"I don't want to blame my mistake on PTSD, but I do want to say it may have been a factor," he told the AP. "My head was not in a place very conducive to a classroom and an academic environment."
In a floor speech last month in which he urged President Obama to show "extreme caution" as he considered a military response to the Sunni Islamist insurgency in Iraq, Walsh discussed his experience fighting there in 2004 and '05, and the toll it had taken on members of his unit. He noted the suicide of one of his men after he'd returned, calling him a "victim of the invisible wounds of war."
"I've seen war up close. And like too many American families, I've seen the costs of war up close," he said.
Walsh's campaign said the senator and his unit had survived hundreds of roadside bombings during his deployment, and he had been targeted by name by Al Qaeda forces in Iraq.
Asked whether Democratic leaders were aware that Walsh had suffered from PTSD, Sen.
Walsh presided over the Senate for the first two hours of its session Thursday, a role often played by more junior lawmakers like him. He later cast a vote on a pending judicial nomination, but otherwise avoided reporters in the hallways and was not seen by others who staked out his office.
The Senate has actually been considering a bill that Walsh had taken a lead role on, the so-called Bring Jobs Home Act, which would close tax loopholes that Democrats say benefit businesses that operate overseas. A nearly identical bill was considered by the Senate in 2012.
"If you dig down a little bit, I don't think it's that big a deal, I really don't," he said. "Look, Walsh is a soldier, he's not an academic. ... And I just think if a person bores down below the surface, it's not near as big a deal as it appears right now."
Asked whether it doomed Walsh's campaign, Tester said, "No, not in the least. Not when the facts come out."
Walsh has been considered an underdog in the Senate race, but just this week Democrats had been touting new poll numbers that showed him closing the gap with his Republican opponent,
Daines, the state's lone representative in the House, has not commented publicly on the plagiarism accusation. But the National Republican Senatorial Committee said the incident "will have serious ramifications" for Walsh.
"There is no excuse for plagiarism as serious as Sen. Walsh is guilty of," spokesmen Brad Dayspring and Brook Hougesen wrote in an email to reporters.
Walsh's campaign said he remains committed to the race.
"Despite an unintentional mistake at the U.S. Army War College, he is back working for and protecting Montana and serving this nation, and we look forward to sharing the contrast to Congressman Steve Daines' record," campaign spokeswoman Lauren Passalacqua said.