The Director of National Intelligence refused Tuesday to comply with a House subpoena for a mysterious whistleblower complaint made last month.

The refusal escalates an already high-stakes standoff between Congress and the political leadership of the intelligence community over lawmakers’ ability to conduct oversight amid allegations that the Trump administration is trying to politicize the country’s spy agencies.

House Intelligence Committee Chair Rep. Adam Schiff (D-CA) had subpoenaed the complaint on Friday after the Intelligence Community inspector general informed Congress that a whistleblower had come forward with a matter of “urgent concern.”

The substance of the whistleblower complaint remains unknown, though it has sparked a confrontation on Capitol Hill between the normally tight-lipped House Intelligence Committee and the Office of the Director of National Intelligence, responsible for overseeing the country’s intelligence community.

Schiff has alleged that the whistleblower complaint points to conduct by President Trump, relying on statements from the DNI that the details of the complaint contain privileged information. In a new letter reviewed by TPM, the DNI’s basis for refusing to hand over the complaint seemed at least consistent with Schiff’s allegation. DNI pegged the refusal to comply with the subpoena on a need to stay in line with the “established confidentiality interests of the Executive Branch” and on “confidential and potentially privileged matters relating to the interests of other stakeholders within the Executive Branch.”

Schiff had said that he would demand that acting DNI Joseph Maguire appear before a congressional panel on Thursday if his office did not comply with the subpoena by the Tuesday deadline. In a Tuesday letter obtained by TPM, Maguire’s office said that it would refuse the demand, calling it “premature.”

TPM reviewed two letters from DNI to Congress, one sent on Tuesday, Sept. 17 and another sent on Friday, Sept. 13. The letters – written by DNI general counsel Jason Klitenic – offer more detail on how the DNI, in self-described consultation with the Justice Department, intercepted a whistleblower complaint that was on its way to Congress.

In the Sept. 13 letter, Klitenic wrote that his office disagreed with the inspector general’s decision to designate the complaint as a matter of “urgent concern,” a legal term whose definition is contained in the statute that governs whistleblower issues within the intelligence world.

But the reason that Klitenic gave for disagreeing with the intelligence community watchdog’s decision could prove to be revealing: he wrote that the allegations in the complaint concern “conduct by someone outside the Intelligence Community” and that they involve “confidential and potentially privileged communications by persons outside the Intelligence Community.”

Klitenic wrote that after receiving the whistleblower complaint from the inspector general, his office “determined, in consultation with DOJ,” that the inspector general had erred in finding that the whistleblower stated an urgent concern.

The DNI lawyer went on to describe the contents of the complaint as “different in kind from that involved in any past cases of which we are aware.”

Upon receiving that letter on Friday, Schiff responded with a subpoena for the complaint and issued a public statement in which he said that the substance of the complaint may go directly to President Trump.

In his Tuesday refusal to comply with Schiff’s subpoena, Klitenic wrote that the Office of the Director of National Intelligence was “committed” to finding “an acceptable accommodation, consistent with the established confidentiality interests of the Executive Branch.”

Klitenic asserted that the DNI had complied with “all applicable law” in refusing to hand over the whistleblower complaint to Congress.

“While we are seeking to expedite consideration of the Committee’s request, it will simply not be possible for the DNI to complete those consultations by this afternoon,” Klitenic wrote.

Schiff told reporters on Tuesday that the acting DNI chief “needs to come in and explain not only to us but to the public why he is ignoring the plain language of the law and whether he’s being instructed to do so.”

Sen. Mark Warner (D-VA) told the Wall Street Journal on Tuesday that “it was our country’s loss” when former DNI Dan Coats was “forced out.” He went on to express concern about “any effort to politicize our intelligence community.”

Read the Sept. 13 letter here:

Read the Sept. 17 letter here: