The White House has been briefed on the Mueller report and, while it will not invoke executive privilege, it has "significant concern" about what is going to be released, according to ABC News' Jon Karl.

"There is significant concern on the president's team about what will be in this report and will be unredacted," Karl told ABC News' "This Week" on Sunday. "The good news is already out there."

Karl was referring to Attorney General William Barr's summary of the Mueller report, which found no evidence of President Donald Trump's campaign conspiring with Russia to meddle in the 2016 presidential election.

Now, the White House will have to take some potential political hits from aspects of special counsel Robert Mueller's investigation, especially the unknown of what former White House legal counsel Don McGahn told investigators during what is reportedly "significantly more than 30 hours with" Mueller's team, according to Karl.

"There is significant concerns about what will be in here – new information on the obstruction of justice question, on what the president was doing regarding some of the big questions," Karl told host George Stephanopoulos.

". . . What worries them most is what Don McGahn told the special counsel. Former White House counsel Don McGahn has visibility on all of this."