(CNN) In recent days, one of Michael Cohen's lawyers has repeatedly changed his account of what Cohen knew about President Donald Trump's involvement in a controversial meeting during the 2016 campaign.

Lanny Davis has offered many variations of his client's knowledge regarding the meeting in Trump Tower but says he is now less certain about Cohen's claims.

"I should have done a much better job of speaking with more suspicion than certainty, and I regret my mistake," Davis told CNN.

On July 26, citing sources with knowledge, CNN was first to report that Cohen, Trump's longtime personal lawyer, claimed he was willing to tell special counsel Robert Mueller that then-candidate Trump knew in advance about the June 2016 meeting in Trump Tower. CNN said Cohen claimed he was present when Donald Trump Jr. told Trump about the Russians' offer to share dirt on Hillary Clinton, and Trump gave approval for the meeting to take place.

CNN stands by its story.

A CNN spokeswoman said Tuesday: "We stand by our story, which had more than one source, and are confident in our reporting of it."

In its story, CNN also reported that when Cohen appeared before the House Intelligence Committee last year, he did not testify that Trump had advance knowledge of the meeting, according to a source familiar with Cohen's House testimony.

The CNN story noted, based on sources, that Cohen did not have corroborating evidence to back up his claim. CNN did not report whether Trump knew about the meeting before it happened -- only that Cohen was making that claim while hoping for a deal from prosecutors.

Davis acknowledged over the weekend that he confirmed CNN's story to other news organizations.

He now says that he also was one of the sources for CNN's story.

For more than three weeks, Davis did not raise any issues to CNN about its reporting.

Last week, Cohen pleaded guilty to eight criminal counts in Manhattan federal court, charges that included tax fraud, false statements to a bank and campaign finance violations tied to his work for Trump.

The guilty plea put new focus on Cohen and the discrepancy over his accounts of the Trump Tower meeting. After Cohen's plea, Davis began to change his story.

When CNN's Wolf Blitzer asked Davis on August 22 whether Cohen had evidence that Trump knew about the meeting beforehand, Davis said: "At this juncture I can only say that he was present during a discussion with Junior and dad, and beyond that, his testimony to the Senate Intelligence and House Intelligence committees was accurate."

Several hours after that, Davis changed his account, this time focusing on Cohen's testimony before Congress last year.

In an interview with CNN's Anderson Cooper, Davis said: "Senator Burr and Senator Warner read the answer to the question about his testimony which is that he said he was not aware ahead of time and did not hear anything to the contrary and that was the testimony."

"He said he wasn't aware ahead of time and did not hear anything to the contrary and that was the testimony before the Senate as well the House Intelligence Committees and he said that testimony was accurate," Davis continued.

When pressed by Cooper on whether Cohen had information on Trump having knowledge about the meeting ahead of time, Davis replied: "No, there's not."

Davis has reversed course from two other claims regarding his client's knowledge of Trump over the past week. One dealt with what Cohen knew about Trump's "awareness" of damaging emails to Clinton's campaign that could have been obtained from hacking. The other concerned a letter that Trump's lawyers allegedly sent the special counsel over hush money payments to two women.

In both cases, Davis walked back initial claims.

Cohen, unlike Davis, has not publicly addressed what he might have said to friends, associates or reporters about these matters.

The meeting at Trump Tower in June 2016 with Russians, Trump Jr., Trump's son-in-law, Jared Kushner, and then-campaign chairman Paul Manafort has become a focal point of Mueller's investigation into Russian interference in the 2016 election.