(CNN) Tennessee Republican Sen. Bob Corker suggested Wednesday that Gens. John Kelly and James Mattis, as well as Secretary of State Rex Tillerson are the "people that help separate our country from chaos," a stinging criticism of President Donald Trump from a man once considered an ally in Washington.

Asked directly by a reporter whether he was referring to Trump in using the word "chaos," Corker, who announced last month he would retire in 2018, responded: "(Mattis, Kelly and Tillerson) work very well together to make sure the policies we put forth around the world are sound and coherent. There are other people within the administration that don't. I hope they stay because they're valuable to the national security of our nation."

Stop for a second and re-read that last paragraph. The sitting Republican chairman of the Senate foreign relations committee is suggesting that if Tillerson was removed from office (or quit), the national security of the country would potentially be in danger. And he's refusing to knock down -- and thereby affirming -- the idea that Trump is an agent of chaos who pushes policies that are not always "sound" or "coherent."

That. Is. Stunning.

Corker also blasted Trump for undermining Tillerson -- most recently with a weekend tweet suggesting that the secretary of state's diplomatic work to solve the North Korea crisis would fail.

"I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man," Trump tweeted Sunday morning.

Corker said that Tillerson is "in an incredibly frustrating place," adding: "He ends up not being supported in the way I would hope a secretary of state would be supported. ... He's in a very trying situation -- trying to solve many of the world's problems without the support and help I'd like to see him have."

Those comments land amid reports that tensions between Trump and Tillerson are worse than ever. They also come on the same day Tillerson held an impromptu press conference to dismiss that he has ever considered resigning his post, but also refused to deny that he had called the President a "moron" during a moment of pique over the summer.

This is also not the first time that Corker, who was once mentioned as a possible vice presidential pick and was on the short list for secretary of state, has been overtly and harshly critical of Trump. Corker drew national headlines in August when he suggested that Trump "has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful."

Trump responded back via Twitter: "Strange statement by Bob Corker considering that he is constantly asking me whether or not he should run again in '18. Tennessee not happy!"

Trump and Corker eventually huddled at the White House to make amends and, according to reports, Trump asked Corker to run for a third term. Less than two weeks later, Corker announced he was retiring.

Corker's comments Wednesday are rightly read as a continuation of his August remarks. Then, he openly questioned Trump's stability and competence. Now he is making clear that if not for Tillerson, Mattis and Kelly, Trump would be leading the nation -- and the world -- into chaos.

There's no question that Corker feels freer to speak his mind without the worry of angering the President and potentially stirring up a serious primary challenge. But what's even more important/scary to contemplate: If this is Corker saying what he really thinks about Trump, what must the rest of Republicans in the Senate and House think of their President? And when will they speak out?