On Tuesday, MSNBC’s Lawrence O’Donnell made a stunning claim on The Last Word: Donald Trump’s tax returns reveal that at least one loan provided to him by Deutsche Bank was co-signed by Russian oligarchs.

As #Resistance Twitter would say…BOOM!

Except, as O’Donnell himself admitted, all of this came from one source who hadn’t seen the bank records! Watch the segment:

Lawrence O'Donnell: Deutsche Bank source says Russian oligarchs co-signed Trump's loans when no other banks would lend to him pic.twitter.com/vk4esVPIeJ — Tex Vet (@TexFarmVet) August 28, 2019

Later in the hour, he clarified that his source was one person, and he hadn't seen the documents. You can see that video at the top of this Mediaite post. “That's going to need a lot more verification before it becomes a confirmable fact,” he said.

Now, look, this is a good story…if it's true. It would explain a lot of the influence Russia seems to have over Trump, and it would give credence to the conspiracy theories that have been circulating since the 2016 campaign. But as every journalist with even the most basic training knows, getting that first source to tell you something intriguing is only step one of a long process that ends with verification from multiple sources, including ones who have seen the documents (along with, hopefully, the documents themselves). Clearly, O'Donnell knew he was sitting on a big nugget, and that nugget was burning a metaphorical hole in his pocket and he didn't have the discipline to wait.

Which, I'm sorry, is unforgivable for a man in his position. Not only because it's irresponsible from a journalistic angle, but because it makes it that much harder for the story to ever come out. And nobody should have to explain this stuff to O'Donnell, who has been in the game for a while.

If you can predict what happened next, it's because you've seen it play out time and again with this Russia hunt—O'Donnell was hit with a strenuous denial from Trump and his team, and a demand for retraction. He should have known this was coming, but that's not all he should have known…he should have known he would be backed into a corner and unable to do anything but concede. I mean, conservative media outright predicted exactly what would happen. Again, he was about 10 percent deep into a reporting process, and when Trump called him out, he had nobody and nothing to lean on except one “source” he couldn't burn who hadn't actually seen the documents.

So, of course, he was forced to issue a retraction, and to admit that his “reporting” fell far short of MSNBC's standards:

WATCH: Lawrence O'Donnell retracts his reporting about Trump loans. pic.twitter.com/JxNsIPhBNg — MSNBC (@MSNBC) August 29, 2019

From there, Trump pounced on O'Donnell, as everyone knew he would. The president is good at smelling blood, and he loves nothing more than an oppositional media figure in retreat. The fact that it played perfectly into his “fake news” paradigm only made the whole episode more perfect:

Crazy Lawrence O'Donnell, who has been calling me wrong from even before I announced my run for the Presidency, even being previously forced by NBC to apologize, which he did while crying, for things he said about me & The Apprentice, was again forced to apologize, this time….. — Donald J. Trump (@realDonaldTrump) August 29, 2019

....for the most ridiculous claim of all, that Russia, Russia, Russia, or Russian oligarchs, co-signed loan documents for me, a guarantee. Totally false, as is virtually everything else he, and much of the rest of the LameStream Media, has said about me for years. ALL APOLOGIZE! — Donald J. Trump (@realDonaldTrump) August 29, 2019

The totally inaccurate reporting by Lawrence O'Donnell, for which he has been forced by NBC to apologize, is NO DIFFERENT than the horrible, corrupt and fraudulent Fake News that I (and many millions of GREAT supporters) have had to put up with for years. So bad for the USA! — Donald J. Trump (@realDonaldTrump) August 29, 2019

The annoying thing here is that, yes, this story could be true! And it would be a legitimate bombshell. But O’Donnell blew it, he looks like an impulsive dilettante with an agenda, and now the people who can cover this kind of thing up—if it’s not total smoke in the first place—have the advance warning they need. All because he lacked patience.

But this isn’t just about O’Donnell, of course. Rachel Maddow has done the exact same thing, on a lesser but more persistent scale, and it’s not confined to MSNBC—Glenn Greenwald at The Intercept documented the ten most embarrassing media failures on Trump-Russia. It’s not enough to attribute this to bad journalism—it’s also about the current media climate, where this kind of “prime the pump” style is rewarded with clicks and views. As Matt Taibbi said, “this is the greatest story that has ever existed for the news media business.” There are implicit rewards for jumping the gun, and very few consequences other than temporary embarrassment. In the meantime, the rush to conclusions before a story is fully reported cuts off the avenues for actually finishing the job. Maybe Buzzfeed was right about Trump ordering Cohen to lie to Congress, and maybe O’Donnell is right that Russian oligarchs backed his loans. But they couldn’t prove it, and the fact that they didn’t hold off until they could makes it very likely that we’ll never know the truth.