“I am in no way, no way, tying what I did to any type of PTSD,” the Montana Democrat said in a Friday interview with KMMS radio in Bozeman. “That had nothing to do with the mistake that I made. … I may have said that, if that was the thought of that, that’s not at all in any way what I meant or said.”

That’s a change from what he said on Wednesday, hours after the New York Times broke the story that Mr. Walsh borrowed liberally from other sources for a 14-page paper at the Army War College. Mr. Walsh had said he was under a great deal of stress following the deaths of members of his military unit.

“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.”