MSNBC host Lawrence O'Donnell issued an on-air clarification Tuesday after making shocking claims about President Donald Trump's ties to Russian oligarchs that had not been vetted by NBC News.

In response to a Democrat-controlled House committee subpoena, Deutsche Bank revealed Tuesday that it was in possession of tax returns "related to" Trump or his immediate family. While the partially redacted filings did not specify whose tax returns the bank possessed, O'Donnell opened The Last Word by claiming they were President Trump's, based on "what one source close to Deutsche Bank has revealed to me."

O'Donnell claimed later in the segment that his source's information "goes a few very important steps beyond" publicly available information, and that "the Trump tax returns reveal that the president pays little to no income taxes in some years."

"The source says that Deutsche Bank is in possession of loan documents that show Donald Trump has obtained loans with co-signers, and that he would not have been able to obtain those loans without co-signers," O'Donnell said. "The source close to Deutsche Bank says that the co-signers of Donald Trump's Deutsche Bank loans are Russian billionaires close to Vladimir Putin."

"If true, that would explain every kind word Donald Trump has ever said about Russia and Vladimir Putin, if true," he continued. "If true, that would be a significant factor in Vladimir Putin's publicly stated preference for presidential candidate Donald Trump over presidential candidate Hillary Clinton."

O'Donnell's tweet teasing the segment also caught fire on Twitter, racking up more than 30,000 retweets as of this writing.

A source close to Deutsche Bank says Trump's tax returns show he pays very little income tax and, more importantly, that his loans have Russian co-signers. If true, that explains every kind word Trump has ever said about Russia and Putin. @TheLastWord 10pm — Lawrence O'Donnell (@Lawrence) August 28, 2019

But closing out the hour, O'Donnell awkwardly returned to the topic and clarified that the network could not confirm his reporting.

"Now, I want to stress, that's a single source. This has not been confirmed by NBC News, I have not seen any documentation from Deutsche Bank that supports this and verifies this," he said. "This is just a single source who has revealed that to me."

"And that's where that stands at this point. It's going to need a lot more verification before that can be a confirmable fact," he concluded.

MSNBC booking producer Michael Del Moro tweeted the following morning that not only has O'Donnell never seen the relevant documents, neither has his source.