President Trump, who maintains the phone call at the heart of the impeachment inquiry was “perfect,” lashed out Monday at House Intelligence Committee Chairman Adam Schiff for saying he didn’t think the person who drew attention to the call would need to testify before Congress.

Schiff, D-Calif., told CBS’ “Face the Nation” Sunday that since impeachment investigators already have the call record, there’s no longer a reason for the intelligence community whistleblower to testify.

"Before the president started threatening the whistleblower ... we were interested in having the whistleblower come forward. Our primary interest right now is making sure that that person is protected," he added.

Trump, who last week called for the impeachment of Schiff and House Speaker Nancy Pelosi, said the whistleblower’s identity must be revealed “to determine why this [the filing of a whistleblower complaint] was done.”

“The Democrats are trashing this president and in the process trashing the U.S. Constitution,” Trump railed, adding he thinks his opponents are “drunk on power.”

The impeachment inquiry centers on a July 25 phone call Trump made to Ukraine President Volodymry Zelensky and the handling of the subsequent whistleblower’s complaint. Just days before the call Trump had frozen nearly $400 million in military aid to the country, which is fighting Russian separatists in its eastern provinces. During that call, Trump asked Zelensky for a “favor” involving an investigation of former Vice President Joe Biden and his son, Hunter. Biden is a leading contender for the Democratic president nomination, and federal election law prohibits foreign contributions to political campaigns.

The inquiry moved ahead Monday with testimony expected from Semyon Kislin, an associated of Trump attorney Rudy Giuliani, and Fiona Hill, the former Russia adviser on the National Security Council. The Ukraine-born Kislin is a New York businessman who contributed to Giuliani’s mayoral campaigns.

Monday also was the deadline for EU Ambassador Gordon Sondland, a major Trump contributor, to provide documents to investigators ahead of his scheduled Thursday testimony. He is expected to say when he assured associates in text messages there was no quid pro quo involved in dealings with Ukraine, he was merely relaying what Trump had told him. Sondland reportedly plans to tell investigators: “It is only true that the president said it, not that it was the truth.”

Sondland’s attorney said, however, his client cannot produce the documents subpoenaed by investigators without State Department approval. The White House has said flatly the administration will not cooperate with the inquiry.

Deadlines expire Tuesday for production of subpoenaed documents from Giuliani concerning his work for Ukraine, Vice President Mike Pence to determine what he knew about Trump’s request to Zelensky, and the Defense Department and Office of Management and Budget to see what led to the freeze in military aid. All have said the documents won’t be forthcoming.