Washington (CNN) A White House official who listened in on President Donald Trump's July call with Ukrainian President Volodymyr Zelensky characterized the conversation as "crazy," "frightening" and was described as "shaken" by the call, according to a memo written by the whistleblower behind the recent intelligence community report about the conversation flagged to Congress.

The memo, a source familiar with the whistleblower report told CNN, was turned over to Inspector General Michael Atkinson who submitted it to Congress.

CNN previously reported that in the hours and days after the Ukrainian President signed-off from the call, nervous word spread among national security aides about the contents of the July 25 call, an early show of worry that Trump's request for an investigation into Joe Biden was far from the "perfect" conversation he now insists transpired.

The scramble and fallout from the call, described by six people familiar with it, parallels and expands upon details described in the whistleblower complaint. The anxiety and internal concern reflect a phone conversation that deeply troubled national security professionals, even as Trump now insists there was nothing wrong with how he conducted himself. And it shows an ultimately unsuccessful effort to contain the tumult by the administration's lawyers.

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