Washington (CNN) President Donald Trump denied again Friday he had instructed his former White House counsel to fire Robert Mueller, contradicting the redacted report Mueller released last week and furthering a battle with Democrats over whether his former lawyer, Don McGahn, should testify before Congress.

It comes as Trump scales up his attacks on Mueller and the report he produced -- broadsides and claims that some view as damaging to an overall legal strategy of asserting executive privilege to prevent key aides from appearing before Congress.

Some West Wing officials have conceded that the President's tweets disputing McGahn's account are not helpful to their case, and fear it could make it more difficult to assert privilege over a conversation that Trump denies occurred.

Mueller's report portrays the President as consumed by the Russia probe and intent on short-circuiting it. Those portrayals have led Democrats on Capitol Hill to issue their own requests for some of the report's key players, including McGahn. But the White House has dug in, refusing to cooperate with the requests and disallowing some aides from appearing before congressional panels.

In the case of McGahn, lawmakers are keen to know what specifically Trump asked in his conversations about the special counsel. In his report, Mueller wrote Trump "called McGahn and directed him to have the Special Counsel removed."

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