Sen. John Thune (R-SD) defended the special counsel put in charge of the Justice Department’s investigation of Russian meddling in the 2016 on Thursday, disputing President Donald Trump’s claim earlier Thursday morning that he was the subject of an investigatory “witch hunt.”

It was far from the first time Trump used that term to define one of the several investigations into his campaign and associates. But it was the first time he used it after the Washington Posted reported that the President is under investigation for obstruction of justice.

The Washington Post first reported Wednesday, citing unnamed people familiar with the matter, that the obstruction of justice probe began just days after Trump fired FBI Director James Comey, on May 9.

“They made up a phony collusion with the Russians story, found zero proof, so now they go for obstruction of justice on the phony story,’ Trump wrote on Twitter Thursday. “Nice.”

“Senator, is Bob Mueller is man of integrity?” MSNBC’s Mark Halperin asked Thune during an appearance on “Morning Joe” Thursday, referring to the special counsel in charge of the investigation. “And has he done anything so far in the conduct of the investigation that leads you to believe he is conducting a witch hunt?”

“No, he is a man of integrity, Mark, and he needs to be able to do his work,” Thune replied. “And I think it’s better for all of us if that work continues. It’s — obviously he is going to get to the bottom and he is going to find the facts, and I think that’s his role. And I think we ought to let him continue to do that and I assume at some point there will be an end to all this. He’ll have done his investigation and there will be whatever findings there are.”

“But I think for now we ought to proceed on our agenda,” he continued. “We ought to try and reform health care, and reform the tax code, and do an infrastructure bill and focus on jobs and the economy for the American people knowing full well that that investigation is going to be ongoing.”

“So not a witch hunt,” Halperin prodded.

“It’s not a witch hunt, no,” Thune said. “You know, I think that he’s got a job to do. I think we all understand that. And I think it’s in everybody’s best interest if we let him do his job, and we do ours.”

Asked by MSNBC’s Ari Melber about how he would advise Trump on the question of dismissing Mueller — which a friend of Trump’s, Christopher Ruddy, recently floated in several interviews — Thune was direct.

“Well, I would certainly advise against that,” he said. “And I don’t think legally he can. I think there are — it sounds like, and I’m not a lawyer — legal grounds for good cause. But I don’t expect that to happen, and I would certainly advise that step not to be taken.”

But, Thune added later, noting the winding paths of special counsels in prior investigations, “I think at some point you have to wrap it up and move on, but we’ve got to let him do that.”