Transcript for Trump’s Ukraine call was described as ‘frightening’: Whistleblower
New reporting here on that triggered the impeachment investigation. The insider at the white house, the official who listened in on the president's call with Ukraine. The whistle-blower saying that that person then described the call as, quote, crazy and frightening. Here's ABC's chief white house correspondent Jonathan Karl. Reporter: Tonight, ABC news has learned a white house official who listened in on the president's phone call with the president of Ukraine described it as crazy and frightening. This, according to the whistle-blower at the heart of the impeachment inquiry. It's perfect. The call was perfect. Reporter: It was on that call president trump told the Ukrainian president, "I would like you to do us a favor" and asked him to investigate a debunked conspiracy theory about stolen democratic emails and Joe Biden and his son. According to the whistle-blower, the white house official on the call reached out to him the next day and was quote "Visibly shaken." The whistle-blower says the official told him the call was completely lacking in substance related to national security. The whistle-blower documented the conversation in a two-page memo and turns it over to the intelligence community's inspector general. So, let's get to Jon Karl, live at the white house tonight, as well. Jon, what are you learning from your sources inside the white house? Are they trying to figure out who this person is on the inside that spoke with the Reporter: Well, David, the president has made it perfectly clear that he wants to know who was talking to the whistle-blower. He's even suggested that person is effectively a spy who should be severely punished. But here's the thing. I've spoken to several senior white house officials about this, none of them say they know of any effort to actually find out who that person was, in fact, I just spoke to a senior official a few minutes ago and said they have no evidence they are trying to find out who was talking to the whistle-blower, despite the fact the president would clearly like to know who that person is. Jon, thank you.
This transcript has been automatically generated and may not be 100% accurate.