President Trump on Monday decried a New York prosecutor’s inquiry into his tax returns as a “continuation of the witch hunt” after a new filing suggested the Manhattan district attorney’s office is pursuing a criminal investigation of the Trump Organization.

Trump, asked about the developments during a press conference at the White House, compared the probe to former special counsel Robert Mueller’s Russia investigation as well as inquiries launched by House Democrats, suggesting it is part of a nebulous, politically motivated conspiracy against his presidency.

“This is just a continuation of the witch hunt. It’s Democrat stuff,” Trump told reporters. “They failed with Mueller. They failed with everything. They failed with Congress. They failed at every stage of the game. This has been going on for three and a half, four years.”

“This is a continuation of the worst witch hunt in American history,” he said before adding that he knew nothing about the investigation.

In a court filing earlier Monday, the Manhattan district attorney’s office argued it is justified in seeking the president’s tax returns, citing media reports about “possibly extensive and protracted criminal conduct at the Trump Organization,” the president’s family business.  

Trump has fought a subpoena from Manhattan District Attorney Cyrus Vance for his financial records. The Supreme Court in a 7-2 ruling in July rejected Trump’s claim that he was immune from a grand jury investigation such as the one led by Vance. Trump’s attorneys have filed a new complaint in the wake of the ruling, arguing that the subpoena is overly broad and amounts to presidential “harassment.”

Vance’s office responded on Monday, arguing that the new complaint fails to put forth valid legal challenges to the subpoena that hadn’t already been presented and rejected by the Supreme Court.

Mueller’s investigation into Trump’s 2016 campaign’s ties to Moscow dogged the first two years of his presidency, and Trump has regularly derided it as a “witch hunt.” The president used the same language to describe House Democrats’ impeachment inquiry, which concluded with his impeachment by the Democratic-majority House and his eventual acquittal by the GOP-controlled Senate earlier this year.