CNN’s presidential historian Douglas Brinkley this morning accused Donald Trump of “big-mouthing” President Obama by speaking out on policy issues during the transition. Co-host Poppy Harlow had teed Brinkely up to slam Trump, worrying that Trump had flouted the “one president at a time” tradition, and fretting that by doing so Trump was “confusing our allies and our adversaries.

Brinkley was only too happy to run with the ball, responding: “I think it’s very wrong-minded of Donald Trump to be doing this . . . what you don’t want to do is to be big-mouthing and big-footing a sitting president . . . . I find it troubling, but I’m not going to be able to stop him from doing it.”

Note: “Big-mouthing?” Is that even a word in the sense Brinkley used it? Looks like the liberal establishment’s contempt for Trump is driving them to new neologistic heights!

POPPY HARLOW: You know, one thing that we’re certainly seeing now is questions about where this one-president-at-a-time practice has gone. You know, all the way back in 2001, George W. Bush, then President-elect, said this: we have one president and we’ll have one president and the current president is President Clinton and our nation must speak with one voice.” Then you had President Obama abiding by that, as well, in 2008. Before he took over when asked about things like the Gaza war, said basically I defer to the sitting president. That has been turned on its head with President-elect Trump, from the call with the Taiwanese president to what he tweeted about Israel and the United Nations decision at the end of last week and Netanyahu. Not to mention the China drone. What does this mean for sort of this practice moving forward and does it confuse our allies and our adversaries?

DOUGLAS BRINKLEY: I think it’s very confusing and I think it’s very wrong-minded of Donald Trump to be doing this. Look, there are different strategies of transition, but what you don’t want to do is to be big-mouthing, big-footing a sitting president. Basically saying ignore anything America does or says for the next month because I’m coming in, new management in town and just don’t listen to President Obama. I don’t think Donald Trump four years from now if he didn’t get re-elected or even eight years would appreciate somebody coming in and acting that way. But we’ve seen this is Donald Trump’s style. He does things differently. I find it troubling, but I’m not going to be able to stop him from doing it.