Though it currently looks like there are 9 competitive races that will determine control of the Senate, some Democrats had hoped to expand the map further, and put Montana's race into play. Most polls have shown the recently-appointed incumbent, Senator John Walsh (D), far behind Representative Steve Daines (R). Yet Walsh, an Iraq veteran, seemed a potentially-plausible candidate, and one recent poll gave Democrats hopes that he might be closing the gap.
These hopes look much less likely after a report by Jonathan Martin of the New York Times revealing Walsh's 2007 master's thesis from the US Army War College was extensively plagiarized. Martin writes that Walsh took "at least a quarter of his thesis" from other sources, and copied his entire concluding section from a Carnegie Endowment for International Peace document. You can take a look at the eye-catching similarities here.
For his part, Walsh told the Times that he "didn't do anything intentional here," and one of his campaign aides "said Mr. Walsh was going through a difficult period at the time he wrote the paper, noting that one of the members of his unit from Iraq had committed suicide in 2007, weeks before it was due," Martin writes.
Some politicians have survived revelations of past plagiarism. While at law school, our current vice president plagiarized about a third of a paper, and he later borrowed rhetoric from a speech delivered by British politician Neil Kinnock without attribution (Biden maintained he usually credited Kinnock, and omitted the attribution only once). Yet for Walsh, who's had trouble even getting his race to be considered competitive, these revelations are a disastrous turn of events.