Sen. Bob Corker blasted President Donald Trump Tuesday morning, shortly before the president was to discuss tax negotiations with lawmakers at lunch, accusing Trump of having "great difficulty with the truth" and predicting his legacy will be the "debasement of our nation."

"I think the things that are happening right now that are harmful to our nation, whether it's the breaking down of — we are going to be doing hearings on some of the things that he purposely is breaking down — relationships we have around the world that have been useful to our nation," Corker told CNN's Manu Raju, and other reporters, in a Capitol Hill hallway interview.

"But I think at the end of the day, when his term is over, I think the debasing of our nation, the constant non-truth telling, just the name-calling . . . I think the debasement of our nation will be what he'll be remembered most for, and that's regretful," he added.

Trump tore into Corker after the live interview aired, ripping him in a pair of tweets slamming his performance.

Sen. Corker is the incompetent head of the Foreign Relations Committee, & look how poorly the U.S. has done. He doesn't have a clue as..... — Donald J. Trump (@realDonaldTrump) October 24, 2017

...the entire World WAS laughing and taking advantage of us. People like liddle' Bob Corker have set the U.S. way back. Now we move forward! — Donald J. Trump (@realDonaldTrump) October 24, 2017

The senator later spoke once again to reporters, after Trump's tweets, and decried the "attempted bullying that he does, which everybody sees through."

"You would think he would aspire to be the president of the United States, and act like a president of the United States," Corker said. "You know, that's just not going to be the case apparently. And it's up to others who serve in an elected capacity, whether they're governor or mayors to conduct themselves in a manner that is more becoming of a leader. But he's obviously, you know, not up to that."

Corker added that he has had private meetings with Trump and had several occasions "where the staff has asked me to please intervene [when he was] getting ready to do something that was off the tracks."

The senator said he is speaking out because he had been in a "pretty tough business, that, you know, started when I was 25," and he's often met up with people with "mentalities of our current president, and have through life just learned how you deal with it."

Corker's strong comments came after appearances on NBC and ABC Tuesday morning, and after he'd said Trump's appearance on Capitol Hill later in the day to talk taxes was little more than a "photo op."

In his earlier hallway interview, Corker did stop short of outright calling Trump a liar.

"We grew up in our family not using the 'L' word, okay, but yeah, just I mean, they're provable untruths," Corker said. "Provable."

Trump has accused Corker, the chairman of the powerful Senate Foreign Relations Committee, of helping President Barack Obama's efforts to push through the Iran nuclear deal, and has said the Republican decided not to seek reelection because he was not getting the president's endorsement.

"On the Iran deal, everybody knows the role I played there and they're working with me, interestingly, right now, on tax reform," Corker said. "A then everything else, four times, he encouraged me to run and told me he would endorse me."

Corker also said he thinks world leaders are "very aware" that much of what Trump says is not true.

"Certainly people here are, because these things are provably untrue," Corker said. "I don't know why he lowers himself to such a low, low standard and debases our country in the way he does but he does."

Corker also said he does not think Trump is a good role model to the nation's children, and that he is "purposely" breaking down relationships around the world.

"I think at the end of the day, when his term is over, I think the debasing of our nation, the constant non-truth telling, the name calling, the things, I think the debasement of our nation will be what he will be remembered most for and that's regretful," Corker said.

"It affects young people. I mean we have young people who for the first time are, you know, watching a president stating, you know, absolute non-truths, nonstop, personalizing things in the way that he does, and it's very sad for our nation."

Corker would not comment directly if he trusts Trump with the nation's nuclear code, but "in our hearing process we will be addressing the fact that he, with only the one other person on the defense side, has tremendous powers . . . I expressed concerns a few weeks ago about his leadership and just his stability and the lack of desire to be competent on issues and understand and, you know, nothing has changed."

The senator said he doesn't want to make the feud between him and Trump as a daily issue, as there is work to do.

"There are some really good people around him and if he would stay out of their way and let them perform, people like [Rex] Tillerson and [James] Mattis and others, you know, we could really make progress on things that matter greatly to our country," he said.