Sen. Bob Corker (R-Tenn.) and President Trump are trading critiques and insults, with Corker saying on Oct. 24 that Trump is "debasing" the nation and should leave tax negotiations and foreign policy "to the professionals." (Bastien Inzaurralde,Jenny Starrs/The Washington Post)

Sen. Bob Corker (R-Tenn.) made the rounds on the morning shows Tuesday, all the while diplomatically doubling down on his recent criticisms of President Trump.

Perhaps as striking was his overall message to the president: Just back off.

On NBC's “Today” show, Savannah Guthrie asked him directly: “Left to his own devices, do you think the president is a threat to national security?” Corker's answer was decidedly not, “No.”

CORKER: I think there are people around him that work in an effort to contain him. That would be [Defense] Secretary [Jim] Mattis and [Secretary of State Rex] Tillerson and General [John] Kelly, there — his chief of staff. I do think . . .

GUTHRIE: Well that almost accepts the premise of the question — if he needs to be contained?

CORKER: I do think when you have the kind of issue we have in North Korea, where we have a very unstable leader there, when you send out tweets into the region to raise tensions, when you kneecap — which is what he's done, publicly — when you kneecap your secretary of state, whose diplomacy you have to depend upon to really bring China to the table to do the things that need to be done — back-channeling in some cases to North Korea — when you kneecap that effort, you really move our country into a binary choice which could lead to a world war. So yes, I want him to support diplomatic efforts — not embarrass and really malign efforts that are underway to try to get some kind of diplomatic solution here. And I think most people would agree with that.

Appearing separately on ABC's “Good Morning America,” Corker more bluntly urged Trump to just stay out of it.

“You're taking us on a path to combat,” he said, adding: “I would just like for him to leave it to the professionals for a while and see if we can do something that's constructive for our country, that region and the world.”

Asked if he was telling Trump to butt out, Corker agreed.

GEORGE STEPHANOPOULOS: Your message to the president: Just leave well enough alone?

CORKER: I would recommend that, based on recent history and just interactions.

Corker then made a similar plea on tax reform: “Hopefully the White House will step aside and let that occur in a normal process. I know recently the White House in a couple cases has been taking things off the table.”

While criticisms of Trump from Republicans have proliferated in recent days, Corker's is different. His is a much more substantive and practical critique. He's basically urging the president to neuter himself and stay behind the scenes, letting senators and his top officials work through the important issues of the day. He's suggesting things would basically work better if the president didn't involve himself at all. That's a remarkable lack of faith in the chief executive.

Sen. Bob Corker (R-Tenn.) again harshly criticized President Trump's effectiveness and character ahead of a lunch with Senate Republicans on Oct. 24. (Jordan Frasier/The Washington Post)

And Trump doesn't appreciate this critique, judging by tweets he fired off shortly after Corker's interviews.

Corker responded:

Corker wouldn't say directly that Trump is a threat to national security, but the idea that the president is an obstacle to a peaceful resolution — and, on a legislative level, to getting tax reform done — is clear from his remarks.

One thing Corker did say it was okay for Trump to do was visit Congress during tax negotiations. But in giving the go-ahead, he suggested it was more of a “photo op.”

“I do look at these things as more of a photo op,” Corker said. “They're not really about substance, but more power to him.”

Or, as Corker would seem to prefer, less power to him.