President Trump continued his weekend-long tirade against Democrats and the whistleblower whose complaint about his interactions with Ukraine have prompted a formal impeachment inquiry, tweeting:

Like every American, I deserve to meet my accuser, especially when this accuser, the so-called "Whistleblower," represented a perfect conversation with a foreign leader in a totally inaccurate and fraudulent way. Then Schiff made up what I actually said by lying to Congress. His lies were made in perhaps the most blatant and sinister manner ever seen in the great Chamber. He wrote down and read terrible things, then said it was from the mouth of the President of the United States. I want Schiff questioned at the highest level for Fraud & Treason. In addition, I want to meet not only my accuser, who presented SECOND & THIRD HAND INFORMATION, but also the person who illegally gave this information, which was largely incorrect, to the "Whistleblower." Was this person SPYING on the U.S. President? Big Consequences!

The big picture: Trump's tweets largely echo comments he made at a private event last week, in which he was caught on tape saying that the whistleblower is "almost a spy" and suggesting that they and the White House sources they relied on may have committed treason.

A number of Trump's allies and most loyal defenders took to the Sunday talk shows to attack the whistleblower's credibility and accuse them of using "hearsay," as Sen. Lindsey Graham put it.

It's correct that the whistleblower was not present for the phone call in which Trump asked the president of Ukraine to investigate Joe Biden, but the summary of the call released by the White House largely corroborates the account detailed in the complaint.

In addition, both the Trump-appointed intelligence community inspector general and acting director of intelligence deemed the complaint to be credible. The acting DNI, Joseph Maguire, said in a hearing last week that the whistleblower "followed the law every step of the way" and "did the right thing."

As for House Intelligence Chairman Adam Schiff, whom Trump is accusing of "treason," he has received criticism for paraphrasing Trump's phone call with the Ukrainian president during the same hearing.

Schiff has been tapped by House Speaker Nancy Pelosi to lead House Democrats' impeachment investigation, which will largely center around Trump's alleged efforts to solicit election interference from Ukraine.

Go deeper: Schiff says House Intel has reached agreement for whistleblower testimony