A former Bill Clinton lawyer has criticized Special Counsel Robert Mueller for failing to draw a conclusion as to whether President Trump obstructed justice during his Russia investigation.

Special Counsel Robert Mueller’s has been slammed by a former Clinton lawyer, who accused the special counsel of "abdicating his duty."

David Kendall, who represented former President Bill Clinton during the independent counsel investigation led by Kenneth Starr, claimed in a fiery new piece for the Washington Post that Mueller had "substantial" evidence in at least 4 of the 10 instances detailed in the report, but refused to do.

He also accused Mueller of failing “to follow Justice Department regulations” when he left the question of whether or not Trump was exonerated from accusations of obstruction open to interpretation by Attorney General William Barr.

The attorney also admonished that hiding behind the Justice Department’s Office of Legal Counsel’s rule is “no justification” for not reaching a clear conclusion at the end of a 2-year investigation.

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The Justice Department’s Office of Legal Counsel’s rule that states a sitting president cannot be indicted on criminal charges because it would impede their ability to lead the country.

“Though the Mueller report said it was not exonerating the president, it left the coast clear for Barr to do just that,” Kendall wrote in the piece.

The piece also charged: "The failure to draw any conclusion on whether the president obstructed justice was a massive dereliction of the special counsel’s duty, and the report’s explanation of this failure is both incoherent and illogical."

After the special counsel's report was submitted, AG Barr subsequently released a memo to the public explaining that Mueller did not reach a conclusion on whether the president obstructed justice yet also did not exonerate him. Barr and Deputy Attorney General Rod Rosenstein, however, determined the evidence did not support such an obstruction case. Mueller later lamented the memo lacked the context to explain the full scope of the investigation’s findings.

Barr has been under scrutiny by the House Judiciary Committee and was questioned by Congress on Wednesday about his handling of the Mueller report. Barr refused to show up for the second day of questioning when Chairman Jerry Nadler, R-NY proposed the attorney general be questioned by committee lawyers, a format Barr did not agree to, prompting Democrats to call for him to be held in contempt of Congress.

The bitter battle of whether or not Trump obstructed justice during the Russia probe heated up on Tuesday as Senate Majority Leader Mitch McConnell urged lawmakers to move on from the Russia scandal.

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"With an exhaustive investigation complete, would the country finally unify to confront the real challenges before us? Would we finally be able to move on from partisan paralysis and breathless conspiracy theorizing? Or would we remain consumed by unhinged partisanship, and keep dividing ourselves to the point that Putin and his agents need only stand on the sidelines and watch as their job is done for them?" McConnell said.