Last month, Michael Cohen’s lawyer, Lanny Davis, confirmed to NBC News a report that Cohen would be willing to tell special counsel Robert Mueller that the president was told in advance about the now-infamous 2016 Trump Tower meeting between members of the Trump campaign team and Russians. But on Tuesday, Davis said he was wrong, and apologized.

After CNN reported that Cohen alleged Donald Trump Jr. notified the president about the meeting in advance, Davis confirmed to NBC News that Cohen would be willing to tell the special counsel just that. But Davis was not willing at the time to be identified by name as a source.

Davis now says that his confirmation was erroneous. "I regret not being much clearer in saying I'm not sure about this story," Davis now tells NBC News. "It's a major mistake for which I am 100 percent sorry. Period. I never should have done it unless I was certain and could prove it."

Davis has said Cohen's testimony to the Senate Intelligence Committee, during which Cohen said he was unaware of the Trump Tower meeting before it was made public in the press last summer, is accurate.

That meeting in June 2016 involved the president's son, his son-in-law, his convicted former campaign manager, and several Russians who claimed to have incriminating information on the president's opponent, Hillary Clinton. It has emerged as a focal point for investigators examining Russia's interference in the 2016 election.

President Trump has insisted he knew nothing about the meeting at the time, tweeting earlier this month, "This was a meeting to get information on an opponent, totally legal and done all the time in politics - and it went nowhere. I did not know about it!"

In a statement to the Washington Post, a CNN spokeswoman said, "We stand by our story, and are confident in our reporting of it."