President Donald Trump on Thursday appeared to walk back his biggest claim about obstruction of justice in the Russia investigation.

After the Justice Department released the special counsel Robert Mueller's report last month, Trump repeatedly boasted that Mueller found "no collusion" and "no obstruction" and that the report was a "total and complete exoneration" of him.

Speaking to reporters on Thursday, however, Trump said there was "essentially" no obstruction.

Trump also went on a lengthy rant about how long Donald McGahn, the former White House counsel, spent testifying to Mueller's team about his interactions with the president.

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President Donald Trump was unequivocal after the special counsel Robert Mueller's findings in the Russia investigation were released last month.

There was "no collusion" and "no obstruction," Trump repeatedly said, adding that Mueller's report represented a "total and complete exoneration" of him.

On Thursday, the president added an important qualifier, telling reporters there was "essentially" no obstruction of justice.

In its report, Mueller's team wrote that it declined to make a "traditional prosecutorial judgment" on whether the president sought to thwart the Russia inquiry.

But it emphasized that this finding "does not exonerate" Trump.

Mueller's team added that it would not draw a conclusion on obstruction because it was constrained by the Justice Department policy that states that a sitting president cannot be indicted.

But prosecutors laid out a road map of all the evidence they had collected in the investigation, including 11 possible instances of obstruction of justice by the president.

Read more: Here are 11 instances of potential obstruction of justice by Trump outlined in the Mueller report

Mueller's team also indicated that it believed Congress would be well suited to investigate the question of obstruction using the evidence in the final report. But Attorney General William Barr concluded before its release that Trump was not guilty of obstruction.

Trump also on Thursday went on a lengthy rant about how long Donald McGahn, the former White House counsel, spent testifying to Mueller's team. McGahn was a critical witness in the obstruction inquiry, and the president has long been frustrated over what he told prosecutors.