(Updates with Army War College opening inquiry)
By Laura Zuckerman
July 24 (Reuters) - The U.S. Army War College has opened an inquiry into accusations that Senator John Walsh, a Montana Democrat now facing a tough election challenge, plagiarized parts of a research paper tied to a master's degree he earned from the school.
The college's announcement on Thursday that it had launched an investigation came a day after the New York Times reported Walsh may have lifted at least a quarter of his master's thesis, citing an examination of the 14-page paper he submitted to obtain his degree in 2007.
Walsh's campaign has said he inadvertently misused citations in what was a research paper, rather than a thesis.
A preliminary analysis of the paper in question led the college to determine that a more thorough examination was warranted by faculty members of an academic review board, which handles cases of suspected plagiarism or misconduct, the school said in a statement.
The college has previously revoked the graduate status of eight former students since 1990, six for plagiarism and two for other types of misconduct, the college said.
"Then and now, we trust our students to uphold high standards of academic integrity," it said.
The New York Times said six recommendations Walsh presented in his paper were taken almost verbatim from a Carnegie Endowment for International Peace document, which he did not cite.
A campaign statement said Walsh "acknowledges the citations were not all done correctly but that it was an unintentional mistake."
It added, "This story will not change Senator Walsh's commitment to his campaign, and it does not change his resolve in dealing with the issues that matter most to Montanans."
Walsh's election opponent, Republican U.S. Representative Steve Daines, did not respond to a request for comment.
Montana's governor on Thursday urged respect for the courage shown by Walsh, an Iraq war veteran and former commander of the Montana Army National Guard, during his military service.
"Senator Walsh has a long history of fighting for Montanans, both at home and in combat," Governor Steve Bullock said.
Bullock added that he had no knowledge of the issues raised the New York Times when he appointed Walsh in February to fill the Senate seat vacated by the retirement of fellow Democrat Max Baucus.
Walsh is up for election to a full six-year term in November as Democrats fight to retain majority control of the U.S. Senate.
University of Montana political science professor Jeffrey Greene said the uphill campaign battle Walsh faces has been made more challenging by the plagiarism claims, which are most likely to discourage swing voters from supporting him.
"Even though he's the sitting senator, he was facing a difficult contest. This makes it worse for him," said Greene. (Reporting by Laura Zuckerman in Salmon, Idaho; Editing by Cynthia Johnston, Mohammad Zargham and Clarence Fernandez)