Bob Corker followed up on his initial response to Trump’s attack on him with some scathing criticism in an interview with The New York Times:

Senator Bob Corker, the Republican chairman of the Senate Foreign Relations Committee, charged in an interview on Sunday that President Trump was treating his office like “a reality show,” with reckless threats toward other countries that could set the nation “on the path to World War III.”

In an extraordinary rebuke of a president of his own party, Mr. Corker said he was alarmed about a president who acts “like he’s doing ‘The Apprentice’ or something.”

“He concerns me,” Mr. Corker added. “He would have to concern anyone who cares about our nation.”

Corker isn’t saying anything that many others haven’t already said, but it is significant that it is coming from such a high-profile elected Republican. The senator was among a very few in the Senate inclined to give Trump the benefit of the doubt in the past, and he sometimes went out of his way to say positive things about Trump’s foreign policy. During the election, he was saying that Trump was bringing a “degree of realism” and “maturity” to foreign policy. That was always wishful thinking, and Corker’s criticism now is a belated admission that he was wrong about all of that. It is fair to fault Corker for not realizing or saying any of these things sooner, but that doesn’t make it any less extraordinary that he is saying it on the record. Thanks to Trump’s foolish attack on him yesterday, he evidently no longer feels obliged to keep quiet about the problems he has with the president.

One of the more interesting things that Corker confirmed concerned Trump’s repeated undermining of Tillerson:

The senator, who is close to Mr. Tillerson, invoked comments that the president made on Twitter last weekend in which he appeared to undercut Mr. Tillerson’s negotiations with North Korea.

“A lot of people think that there is some kind of ‘good cop, bad cop’ act underway, but that’s just not true,” Mr. Corker said.

Without offering specifics, he said Mr. Trump had repeatedly undermined diplomacy with his Twitter fingers. “I know he has hurt, in several instances, he’s hurt us as it relates to negotiations that were underway by tweeting things out,” Mr. Corker said.

We already knew this, but it is important that someone in Corker’s position is acknowledging that the administration’s foreign policy is every bit as dysfunctional as it appears to be. It remains to be seen whether Corker’s break with Trump will translate into meaningful opposition to any part of Trump’s foreign policy, but his remarks in this interview suggest that it might.