Sen. John Walsh, D-Mont., announced Thursday that he will abandon his bid for a full term in the Senate after a plagiarism scandal sent his campaign into a downward spiral.

“I am ending my campaign so that I can focus on fulfilling the responsibility entrusted to me as your U.S. senator,” Walsh said in a statement, as reported by the Billings Gazette. “You deserve someone who will always fight for Montana, and I will.”

Walsh said he plans to serve out the remainder of his term as a senator.

Already hampered by disappointing polling, Walsh's campaign was sent into a tailspin two weeks ago after the New York Times uncovered multiple instances of plagiarism in Walsh's final paper at the United States Army War College, where he received a master's degree. Walsh's campaign blamed the plagiarism on his PTSD from military combat overseas.

Montana Gov. Steve Bullock appointed Walsh, his lieutenant governor, to the Senate earlier this year when Max Baucus retired to become the U.S. ambassador to China. Republicans decried the choice as a "Big Sky Buy-Off" to help boost Walsh in his Senate bid.

Still, Walsh was never able to match his Republican opponent Rep. Steve Daines in the polls, though Walsh's standing did show some improvement in the weeks before the plagiarism scandal broke. Even then, many Democrats had written off the race as a lost cause.

It will now fall to Montana Democrats to select a new nominee at a convention by Aug. 20. The Democratic Senatorial Campaign Committee did not immediately respond to a request for comment.