White House staff 'babysat' Donald Trump's calls with world leaders 'as he wouldn't have his facts straight'

Trump pictured on the phone to Russian President Vladimir Putin in 2017 surrounded by senior White House figures. (Reuters)

White House staff frequently had to sit in on Donald Trump’s phone conversations with other world leaders over fears he “wouldn’t have his facts straight”, it has been claimed.

A source within the White House told CNN that the practise became commonplace during the tenure of White House chief of staff John Kelly, as Trump’s advisers attempt to stop him saying anything inappropriate.

The staffer said that up until Kelly’s departure in December last year, Kelly and other aides would often “babysit” calls to foreign leaders

"Kelly always wanted a bunch of us to be there in the Oval (Office) to just babysit on these calls," the source said.

Staff were reportedly worried that the President would get his facts wrong. (Reuters)

"He would go on random tangents about the Mueller investigation with foreign leaders it was unnecessary and unhelpful.

"And sometimes he just wouldn't have his facts straight and he would really rattle some of the foreign leaders with whom he spoke."

According to the source, when there was a long translation happening on the other end Kelly would reportedly mute the President’s phone so that “staff in the room could give guidance”.

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The source added: "Eventually they figured it out and they adjusted, but those calls were nothing like what a normal call would be between presidents."

"We were there to coach him in real time, because he was so impervious to coaching ahead of time," the source said, but conceded that "if the President was determined to say something, you couldn't really press mute."

It is unclear whether the controversial call between Trump and Ukrainian President Volodymyr Zelensky was conducted in front of White House staff.

The impeachment probe has gathered pace since the emergence of details about the call, in which Trump allegedly asked Zelensky to investigate Joe Biden’s son for corruption.

The Democratic-led House initiated an impeachment inquiry against Trump last week after a whistleblower report raised concerns that Trump tried to leverage nearly $400 million in U.S. aid in exchange for investigating Biden from Ukraine's leader in July.

Secretary of State Mike Pompeo reportedly took part in the July 25 phone call between Trump and Zelenskiy, but is unclear who else was there.

Lawmakers now face a delicate task as they try to obtain testimony from the person who blew the whistle on President Donald Trump and Ukraine.

They say they are concerned for that person's safety, especially in light of the president's tweets suggesting he believes the person's actions could be treasonous.