REUTERS/Jonathan Ernst
Trump's ex-White House counsel said he felt "frustrated, perturbed, trapped" when Trump asked for his help firing Mueller.
He also said that he tried to "get off the phone" when Trump raised the subject.
Don McGahn made the comments while testifying to Congress last week about the Mueller probe.
Former White House counsel Don McGahn testified to Congress last week that he felt "trapped" when then President Donald Trump asked him to help engineer the removal of the special counsel Robert Mueller during the Russia investigation.
McGahn was a central witness in Mueller's inquiry into whether Trump obstructed justice as part of the Russia probe. Last week, in closed-door testimony before the House Judiciary Committee, McGahn recounted what it was like when Trump called him in 2017 and asked him to direct then acting attorney general Rod Rosenstein to fire Mueller.