President Trump attacked the impeachment investigation Friday as a “hoax” and “witch hunt,” saying House Democrats should not be holding public hearings.

Democrats have scheduled the hearing to begin next week with testimony from three veteran diplomats. As a runup to the public phase of the investigation into whether Trump abused the power of his office, lawmakers have been taking depositions behind closed doors and earlier this week began releasing transcripts.

“They shouldn’t be having public hearings,” Trump told reporters as he left the White House for an appearance in Georgia. “This is a hoax. This is just like the Russian witch hunt,” a reference to the special counsel investigation that found Russia had interfered in the 2016 presidential election in Trump’s favor.

Trump’s remarks broke with the position of fellow Republicans, who have been clamoring for a public investigation.

Trump said early on he would not cooperate with the inquiry into whether he pressured Ukraine to dig up dirt on his political opponents in exchange for $391 million in military aid until Democrats took a formal vote on conducting an investigation.

But since that vote was taken two weeks ago, the White House continued to encourage administration officials and staff to defy subpoenaes.

Acting White House Chief of Staff Mick Mulvaney became the latest administration figure to do so. His attorney told impeachment investigators the White House had asserted “absolute immunity.”

House Judiciary Committee Chairman Jerry Nadler, D-N.Y., told CNN White House stonewalling is wrong but he doesn’t think it will prevent the investigation from moving forward, noting evidence produced so far “confirms the same story,” that Trump “sought to extort a foreign country into intervening in an American election.”

“Eighty percent of the American people know that that’s wrong, and it’s clearly wrong,” Nadler said.

Nadler noted the courts have been upholding House subpoenas compelling testimony, making defiance a losing strategy.

House Democrats hope to hold an impeachment vote by late December but the timing will depend on the extent of any defense offered by Trump before the Judiciary Committee, which takes over the lead from the Intelligence Committee to compile a list of charges.

Transcripts released this week indicated diplomats were concerned about the role Trump attorney Rudy Giuliani was playing in the administration’s Ukraine police. Former Ambassador Marie Yovanovitch accused Giuliani of running a smear campaign that led to her ouster.

Trump has tried to downplay the testimony, claiming it came from people with whom he was unfamiliar or never-Trumpers.

“Nobody has any first-hand knowledge,” Trump said, adding that the only thing that counts is the reconstructed transcript of the “perfect” July 25 phone call he made to Ukraine President Volodymyr Zelensky during which he asked Zelensky to do him a “favor” by investigating former Vice President Joe Biden and debunked conspiracy theories that Ukraine, not Russia, intervened in the 2016 presidential election.

Trump said Friday he is considering the release of a transcript of another call he made to Zelensky just days after the comedian-turned-politician was elected president in April.

Attorneys for the whistleblower whose complaint triggered the impeachment inquiry issued a cease-and-desist letter to the White House, accusing Trump of putting their client and his family in danger with his abusive rhetoric.

Trump has charged the whistleblower is a Democrat who was in cahoots with House Intelligence Committee Chairman Adam Schiff, D-Calif.