MSNBC host Lawrence O'Donnell began his show Tuesday night with a bombshell allegation

Highlights MSNBC host began his show on Tuesday with a bombshell allegation

Russian billionaires "close to Putin" signed a loan for Trump, he claimed

Later distances himself from the allegation, calls it "error in judgment"

MSNBC host Lawrence O'Donnell began his show Tuesday night with a bombshell allegation: that Russian billionaires "close to Vladimir Putin" had co-signed a loan that was given to President Donald Trump by a foreign bank.

The brief report, which O'Donnell credited to a single source, was yet another piece of intrigue about Trump's finances and connections to Russia, a major point of inquiry the past few years.

But O'Donnell distanced himself from the allegations Wednesday, saying his report was "an error in judgment" that hadn't gone through the network's verification and standards process.

"I shouldn't have reported it and I was wrong to discuss it on the air," he said, promising to address the issue on his show Wednesday.

He did not explicitly say whether he believed the report to be erroneous or not.

O'Donnell had stressed that the report was unverified Tuesday night, noting that it would be a big deal "if true." He later noted that it was not confirmed by news reporters at MSNBC's parent company, NBC.

"I have not seen any documentation from Deutsche Bank that supports this and verifies this. This is just a single source who has revealed that to me," he said.

Other outlets failed to confirm the reporting, as well. The report came on the heels of the disclosure that Deutsche Bank had some of the personal tax records that Trump has sought so desperately to shield from public view. The records are the subject of multiple inquiries in the House of Representatives.

Trump has sued to try to stop the banks and his accounting firm from complying with congressional subpoenas.

Earlier on Wednesday, Charles Harder, a lawyer for Trump, had sent a letter to NBC demanding that it "immediately and prominently retract, correct and apologize" for the report, which it said was "false and defamatory."

"The only borrowers under these loans are Trump entities, and Mr. Trump is the only guarantor," Harder wrote. "Numerous documents for each of these loans are also recorded, publicly available and searchable online. Thus, actual malice can easily be proven based on your reckless disregard of the truth and unreasonable reliance on an alleged "source" who you will not even identify in your story and likely is seeking to mislead you and the public for political reasons or other ulterior motives."

On Twitter, Eric Trump called the report "a reckless attempt to slander our family and smear a great company. Apologies are not enough when the true intent was solely to damage and cause harm. As a company, we will be taking legal action."

MSNBC did not respond to an immediate request for comment.