"That's why they keep saying, 'Oh, the whistleblower said this or that,'" he said. "What happened is, if they would've seen the transcript early, they wouldn't have had a whistleblower because he wouldn't have said - there was nothing he could say. All you have to do is read the transcript."

Trump brushed off that, according to a memo the whistleblower wrote one day after the call, a White House official described the Trump-Zelensky call as "crazy" and "frightening" and that aides quickly became concerned about containing the fallout from the call. He called the growing scandal a "con being perpetrated on the United States public."

That's why, he said, "I don't know why a person that defrauds the American public should be protected, OK?"

The president has sought to undermine the whistleblower on a daily basis in the weeks since news of the complaint broke. He's been aided by allies, conservative media outlets and internet sleuths who have seized on the intelligence community inspector general's acknowledgment that the complainant exhibited "some indicia of an arguable political bias ... in favor of a rival political candidate," though the complaint was deemed credible regardless.

Over the past 24 hours, several media outlets that in congressional testimony, the intelligence community watchdog told lawmakers the whistleblower had "some type of professional relationship" with a Democrat running for president.

But lawyers for the whistleblower tried to shut down the criticism in a statement released Wednesday evening. They denied that their client ever "worked for or advised a political candidate, campaign, or party," adding that the whistleblower had served in apolitical roles, encountering politicians from both parties in those government roles.

They also noted that the whistleblower provided relevant career information to the inspector general so he could assess the credibility of the complaint, and they again pointed out that the complaint was deemed credible.

Finally, they said: "the whistleblower is not the story. To date, virtually every substantive allegation has been confirmed by other sources. For that reason, the identity of the whistleblower is irrelevant."

Trump's litany of attacks have prompted concerns for the whistleblower's safety, and experts have said there is probably no statute blocking Trump from disclosing his or her identity to the public. In a letter to the acting director of national intelligence last month, the whistleblower's attorneys raised worries about their client's safety.

Meanwhile, House Democrats looking to speak to the whistleblower for their impeachment investigation have reportedly considered taking extreme steps to safeguard the whistleblower's identity.