Sunday's big Washington story was the escalating feud between Donald Trump and Sen. Bob Corker, R-Tenn., the retiring Senate Foreign Relations Committee chairman, with the senator giving several juicy quotes to The New York Times about Trump's lack of fitness for the office he holds.
And as usual when prominent Republicans attack Trump in shocking and unprecedented ways, a whole lot of pundits and Trump opponents, especially liberal opponents, seem most interested in finding fault not with Trump but with the one making the comments. Why didn't he say something like this before? What good is saying anything when it's action that matters? What will he do now — will he oppose Trump with every vote he casts in the Senate, or is he still going to vote for tax cuts and the Republican health-care legislation?
Sure, there's always something more anyone can do.
But for a Republican senator to say of the Republican president, as Corker tweeted Sunday morning, that "the White House has become an adult day care center" is a very big deal indeed.
Never miss a local story.
For that senator to say "the vast majority of our caucus understands what we're dealing with here" in terms of the president's lack of fitness for office is enormous. For perhaps the Republican senator with the strongest reputation on foreign affairs to say that the president was risking "World War III" isn't just talk; in politics, talk often is action.
People talk about the danger of "normalizing" what Trump does. And that's a real danger. But it's just as dangerous to treat this kind of extraordinary reaction to Trump as if it's normal. It is not.
Senators, even ones who are retiring and have no fear of electoral retribution, simply don't talk that way about same-party presidents. Certainly not on the record. Certainly not claiming that their views are widely shared by the rest of the party.
And it matters. Public opinion strongly tends to follow highly visible party leaders, but that can't happen if the news media doesn't find a way of explaining just how remarkable these kinds of statements are.
No, it's not that Republican voters all would take Corker's side against Trump even if they were aware of what he said. But all Republicans don't need to defect for Trump to be badly damaged. He was elected because a whole lot of Republicans who didn't like him very much voted for him anyway; if those weak supporters abandoned him, he would be in big trouble indeed.
In the meantime, it will be interesting to see what Corker does in the Senate to follow up on his public statements. Don't expect any Republican, however, to suddenly turn against the Republican agenda — which, after all, they believed in long before Trump was around — simply in order to hurt the president.
And in my view, Trump opponents should take allies wherever they can find them and emphasize how broad the coalition against the president is, rather than attacking newly public converts for showing up too late or doing too little.
Jonathan Bernstein is a Bloomberg View columnist.