U.S. President Donald Trump, faced with a mounting impeachment inquiry, said Monday that written answers are not good enough from the whistleblower who first disclosed that he had pressed Ukraine to pursue investigations of one of his chief 2020 Democratic political rivals, former Vice President Joe Biden.

“He must be brought forward to testify,” Trump said on Twitter regarding the whistleblower. “Written answers not acceptable!”  He called the impeachment investigation a “con.”  

The Whistleblower gave false information & dealt with corrupt politician Schiff. He must be brought forward to testify. Written answers not acceptable! Where is the 2nd Whistleblower? He disappeared after I released the transcript. Does he even exist? Where is the informant? Con!

— Donald J. Trump (@realDonaldTrump) November 4, 2019

Trump offered his latest assessment on the impeachment effort targeting him in the House of Representatives a day after a Washington lawyer, Mark Zaid, said his client, the unnamed whistleblower, would be willing to answer questions in writing posed by Republican supporters of Trump, other than queries about his identity. Republican lawmakers also said the conditions were unacceptable.

“What I said on the phone call with the Ukrainian President [Volodymyr Zelenskiy] is ‘perfectly’ stated,” Trump tweeted. “There is no reason to call witnesses to analyze my words and meaning. This is just another Democrat Hoax that I have had to live with from the day I got elected (and before!). Disgraceful!”    

What I said on the phone call with the Ukrainian President is “perfectly” stated. There is no reason to call witnesses to analyze my words and meaning. This is just another Democrat Hoax that I have had to live with from the day I got elected (and before!). Disgraceful!

— Donald J. Trump (@realDonaldTrump) November 4, 2019

Trump on Sunday derided the whistleblower, linking him to his Democratic predecessor, President Barack Obama, along with former CIA director John Brennan and former national security adviser Susan Rice — two of Obama’s top aides.

“There have have been stories written about a certain individual, a male, and they say he’s the whistleblower,” Trump said at the White House. “If he’s the whistleblower, he has no credibility because he’s a Brennan guy, he’s a Susan Rice guy, he’s an Obama guy. And he hates Trump.”

“Now, maybe it’s not him. But if it’s him, you guys ought to release the information,” the president urged reporters.

Zaid, the whistleblower’s lawyer, said his legal team has offered to allow Congressman Devin Nunes, the top Republican on the House Intelligence Committee, to submit questions which the whistleblower would answer “in writing, under oath and penalty of perjury.”

But Congressman Jim Jordan, the top Republican on the House Oversight Committee, objected to the proposed process, saying written answers would not give Republicans a chance to cross-examine the whistleblower.

“You don’t get to ignite an impeachment effort and never account for your actions and role in orchestrating it,” Jordan said in a statement.  “We have serious questions about this individual’s political bias and partisan motivations and it seems Mark Zaid and Adam Schiff [the Democrat leading the impeachment probe] are attempting to hide these facts from public scrutiny.”

Zaid responded on Twitter, saying Jordan’s statement showed a “misunderstanding” of federal whistleblower protections.

Those laws protect the identity and careers of people who report issues such as misconduct, abuse of authority and dangers to public safety by government employees.

The whistleblower reported being “deeply concerned” about Trump’s July 25 telephone call with Zelenskiy in which Trump urged the Ukrainian leader to investigate Biden for alleged corruption, his son Hunter Biden, who worked for a Ukrainian natural gas company, and any efforts Ukraine undertook to try to defeat Trump in the 2016 election.

Although the whistleblower gave a second-hand account of the Trump phone call, witnesses who heard the call directly have verified much of what he said, as did a rough transcript of the call released by the White House.  

Despite laws protecting government whistleblowers, Trump demanded again Sunday that the whistleblower be revealed.

“The Whistleblower got it sooo wrong that HE must come forward,” Trump tweeted. “The Fake News Media knows who he is but, being an arm of the Democrat Party, don’t want to reveal him because there would be hell to pay,” Trump said. “Reveal the Whistleblower and end the Impeachment Hoax!”

Trump insisted that he does not know who the whistleblower is, although he keeps referring to that person as “he” and says it’s an “Obama guy.”

The Democratic-led impeachment probe is centered on whether Trump called on a foreign government — Ukraine — to interfere in next year’s election and withheld $391 million in military aid unless Zelenskiy publicly committed himself to investigating Biden and the Democrats.

White House aide Kellyanne Conway told CNN Sunday that Trump’s request was not an impeachable offense.

“Nothing would lead to a high crime or misdemeanor,” she said. “I feel comfortable in saying that [Trump] never mentioned a quid pro quo or 2020,” Conway said, adding that Ukraine eventually got the military aid Trump temporarily froze.