There is no one busier or with a more thankless job in American journalism than Daniel Dale, CNN's very own Trump fact checker.
If you follow Dale on Twitter, he attends every Trump event and dutifully notes every statement by Trump in real time.
At his Mississippi rally last week, Dale was there when Trump just bald-faced lied to his fans about something that they could see with their very own eyes wasn't true.
President Donald Trump stood before thousands of supporters in Mississippi on Friday night, squinted and pointed, and told them he was seeing something that was not actually happening.
Trump criticized CNN at length at his campaign rally in Tupelo. Then he gestured toward the back of BancorpSouth Arena and informed the crowd that he had just seen the light on CNN's camera go out.
"Their light just went off. See? Look. Their light was on -- they just turned it off," he said.
When the light is on, he explained, "that means you're live." CNN had stopped broadcasting live, he said, because it didn't want to air his scathing criticism.
He made up this whole story.
Facts First: CNN was never broadcasting the rally live. CNN was not providing the live "pool" feed to other television networks. CNN's photojournalist on the scene did not stop recording at any point in the speech. And the light on his camera is set so that it does not go on and off at all. CNN.com streamed the live rally online.
That Donald Trump is a pathological liar is not a surprise. That he lies about something so obvious and that anyone in the same room can see is false is a level of pathology that even Dale can't believe, as he tells Reliable Sources host Brian Stelter.
"I think he's given us reason to doubt literally everything he's saying. I think one of the things that distinguishes Trump as a liar is he lies about even the most trivial stuff, the most obvious stuff. It's not just the typical political lying to defend one against a scandal. He is proactively lying about stuff all the time."
He no longer deserves the benefit of the doubt that even Dale will still give him. It's just time for the media to show what he really is.
