By just before 9 a.m. Tuesday, Sen. Bob Corker (R-Tenn.) was already a man unburdened.

Corker, the chairman of the powerful Senate Foreign Relations Committee, had appeared early on three major morning shows — ABC, CBS and NBC — ostensibly to preview his party's tax plan ahead of President Trump's visit to the Capitol on Tuesday for a lunch with Senate Republicans.

But before the morning shows had even wrapped, Corker had ratcheted up his already simmering and deeply personal feud with the president — prompting a flurry of retaliatory tweets from Trump. The spat served to ensure that the chaos and feuding that has come to define Trump's young presidency would yet again distract from a day originally intended to focus on tax reform.

During a trio of harsh television interviews, Corker called Trump "utterly untruthful," expressed hope that he would stand aside to allow Congress to formulate a tax plan, worried aloud about the president's divisive governing style and, speaking about ongoing tensions with North Korea, told ABC's "Good Morning America" that he would like to see Trump "leave it to the professionals for a while."

"The president continues to kneecap his diplomatic representative, the secretary of state, and really move him away from successful diplomatic negotiations," Corker said. "You're taking us on a path to combat."

In one particularly striking interview with CNN, Corker in the span of three minutes called Trump what he dubbed "the L-word" (the president, he said, "has great difficulty with the truth"), said he would not support him for president again ("no way") and called for Trump's staff to better manage him (he said he hopes West Wing aides would "figure out ways of controlling him"). 

Senate Foreign Relations Committee Chairman Sen. Bob Corker (R-Tenn.) talks to reporters about President Trump on Tuesday on Capitol Hill. (J. Scott Applewhite/AP)

"I don't know why he lowers himself to such a low, low standard and debases our country in the way that he does, but he does," Corker said, adding that he wasn't sure Trump was a good role model for children.

The Tennessee Republican recently announced that he is not running for reelection, and his lame duck status seems to have liberated him to more forcefully speak his mind. 

Corker's succession of brittle comments seemed to enrage Trump — who often spends his mornings flipping between channels — and the president responded with several tweets. Using his favorite diminutive nickname for the short-statured senator — "liddle'" — the president called Corker "a lightweight" and "the incompetent head of the Foreign Relations Committee," blaming him for having "set the U.S. way back."

Corker, who earlier this month had warned that Trump's recklessness could launch "World War III" and evocatively described the White House as "an adult day-care center," responded in kind on Twitter.

"Same untruths from an utterly untruthful president. #AlertTheDayCareStaff," Corker wrote after Trump's first missives, essentially calling the president a liar.

The entire back-and-forth took place before lunchtime, when Trump is meeting with Senate Republicans, including Corker, to help push through a tax plan that, if successful, would mark the administration's first major legislative achievement.

Tuesday's back-and-forth underscored just how much Trump and Corker's relationship has deteriorated in recent months — a vitriolic personal feud that has spilled over into public view, threatening to overwhelm the president's already struggling legislative agenda.

Corker supported Trump's campaign — serving as a human vouchsafe for a man many in his own party did not entirely trust with the nuclear codes — and was initially under consideration both as Trump's vice president or secretary of state. But Corker quietly began to sour on the president, especially as he watched him careen across the world stage, saying Trump was dangerously upending years of global policy. 

In August, following the racially motivated violence that left one woman dead in Charlottesville, Corker publicly slammed Trump for saying there were "fine people on both sides. "The president has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate to be successful," Corker said then.

Then, two months later, in a deliberate interview with the New York Times, Corker laced into Trump again, criticizing him for running the West Wing like a "reality show" and warning that he could be leading the nation down "the path to World War III."

At that point, the relationship seemed damaged beyond repair, although Corker indicated that he might still vote for a Republican tax plan if he believed it wouldn't add to the deficit. 

 But Tuesday's rift could further complicate Trump's legislative agenda, especially if Corker is giving voice — as he has claimed previously — to concerns other Republicans have but are skittish to articulate aloud. 

Corker had no such qualms Tuesday. He said during the CNN interview that Trump, who had never held elected office until winning the White House in November 2016, has not grown into his job as president. "He has proven himself unable to rise to the occasion," Corker said. "He's obviously not going to rise to the occasion as president."

If Corker's words were harsh — and, as some in his own party argued, contributing to an unhelpful internecine Republican feud — the Tennessee senator seemed liberated. Later Tuesday, speaking to reporters in the hallways of Congress, he continued his broadside, saying: "I've seen no evolution in an upward way. As a matter of fact, it seems to me it's almost devolving."

The White House did not respond to request for comment, but in a Fox News interview, press secretary Sarah Huckabee Sanders called Corker "ineffective," arguing that Trump is eager to make progress on a host of issues, including taxes, the Iran deal and North Korea.

"I think you have one or two people who don't want to see the ball move further down the field," she said. "This is a president who wants to be aggressive, wants to take action. And if Sen. Corker doesn't want to be a part of that, then I think that's sad for his constituents, but we're not going to let that get in the way of us moving forward."