Trump blasts CNN, which stands by Trump Tower report

Despite a key source backing off his assertion, CNN is sticking by a story casting doubt on President Donald Trump's claim that he did not have prior knowledge of a June 2016 meeting with a Russian lawyer to get damaging information on Hillary Clinton.

CNN said it had more than one source for its story, co-authored by Jim Sciutto and Carl Bernstein, best known for his reporting for the Washington Post on the Watergate scandal.

CNN's story, written on July 27, said that Trump's former lawyer Michael Cohen was willing to say that he heard Trump's son, Donald Trump Jr., tell his father about the Russians' offer to share material about Clinton, his Democratic rival for the presidency.

It also said that Trump gave the go-ahead to take the meeting at Trump Tower. If true, that would contradict what Trump and representatives have long said, that he didn't know about the meeting until long after it happened.

Such information would be of great interest to special counsel Robert Mueller and his investigation into Russian involvement in the 2016 American presidential campaign.

Cohen's lawyer, Lanny Davis, has recently taken back earlier remarks, and now says that he is no longer certain that Cohen could legitimately claim Trump knew about the meeting, and that he didn't have information to prove it. He said he was a source for other news organizations that tried to match CNN's original story and, indeed, that he was a source for CNN.

CNN, in its story on Tuesday, quoted Davis as saying, "I should have done a much better job of speaking with more suspicion than certainty, and I regret my mistake."

CNN says they reported a claim

Some CNN critics wondered if Davis's subsequent statement meant that CNN should retract its entire story. But CNN made a distinction: its original story did not assert that Trump definitely knew about the meeting ahead of time only that Cohen had been making the claim while talking with prosecutors.

CNN said on Tuesday that it "we stand by our story, which had more than one source, and are confident in our reporting of it."

Trump tweeted Wednesday: "CNN is being torn apart from within based on their being caught in a major lie and refusing to admit the mistake." He also launched a personal attack against Bernstein, accusing him of "making up story after story."

CNN responded with a tweet saying it "stands by our reporting and our reporters."

Bernstein also tweeted, saying: "I have spent my life as a journalist bringing the truth to light, through administrations of both parties. No taunt will diminish my commitment to that mission."

Trump continued his attacks on the media and the use of anonymous sources on social media early Thursday.

On Tuesday, Trump tweeted claims that China hacked Hillary Clinton's emails when she was secretary of state and used a homebrew server. The only published item related to the claim that day had been from the right-wing news site The Daily Caller, based on two anonymous sources.

With files from CBC News