The White House budget office is refusing to comply with a House subpoena for documents involving President Trump withholding military aid to Ukraine, setting up a power struggle as Democrats pursue impeachment.

The budget office attacks the Democratic inquiry as illegitimate in a written rebuttal, the content of which was first reported by the Washington Examiner.

In a letter sent to the House Intelligence Committee Tuesday evening, the office cites the lack of a vote to begin an impeachment inquiry, longstanding privileges shielding executive branch documents, and the vagueness of the Democratic subpoena.

A senior administration official told the Washington Examiner the decision was made because House Democrats have "no guardrails, no scope, no process laid out to allow folks within the administration to properly respond."

Russ Vought, acting director of the White House Office of Management and Budget, was subpoenaed last week by the House Intelligence Committee, which is leading an impeachment inquiry into Trump. His refusal to comply builds on broader White House rejection of the legitimacy of proceedings, as laid out in a declaration this month drafted by White House counsel Pat Cipollone.

"The House of Representatives has yet to authorize such an inquiry," the budget office contends in the response. "The Supreme Court has long held that the first step in assessing the validity of a subpoena from a congressional committee is determining 'whether the committee was authorized' to issue the subpoena, which requires 'constru[ing] the scope of the authority which the House of Representatives gave to' the committee."

Democrats want to determine the timing of Trump's decision to withhold hundreds of millions of dollars in military aid to Ukraine, and the association with a July 25 request from Trump that Ukraine investigate Joe Biden and his son Hunter, who served on a Ukrainian energy company's board. Trump has attacked the probe as a "kangaroo court."

The Intelligence Committee subpoena was issued in cooperation with two other House committees participating in Democrats' impeachment proceedings. Republicans have objected to the closed-door proceedings of Intelligence Committee deliberations and witness interviews.

"In marked contrast with historical precedents, the House has not expressly adopted any resolution authorizing an impeachment investigation," the letter says.

The subpoena sought records related to withholding Ukrainian aid and threatened Vought that his "failure or refusal to comply with the subpoena, including at the direction or behest of the President or the White House, shall constitute evidence of obstruction of the House's impeachment inquiry and may be used as an adverse inference against you and the President."

The office fires back in its letter: "OMB objects to this extraordinary threat. Invoking reasonable legal defenses to a subpoena, including invoking privileges that are held by the President, in no way manifests evidence of obstruction or otherwise warrants an adverse inference. Indeed, the very idea that reasonably asserting legal rights is itself evidence of wrongdoing turns fundamental notions of fairness on their head and is inconsistent with the rule of law."

Although escalating a clash between branches of government, struggles over the appropriateness of subpoenas is nothing new. During the Obama administration, the executive branch refused to comply with various subpoenas, including for documents in the "Fast and Furious" scandal involving gun smuggling to drug cartels and regarding the energy company Solyndra, which went bankrupt after taking government funds.

Some Obama-era subpoena fights ended with Congress backing down. Others ended in contempt votes, which the Justice Department declined to enforce.

Today, the office cited the short time frame as making document production impractical.

"Given the broad scope of your request, the time required to collect the documents, review them for responsiveness and relevant privileges, and produce responsive, non-privileged documents to the committee is not feasible, within the mere eight days afforded to OMB," the letter says.

In addition, the office cites historical practice.

"Consistent with the actions of prior Administrations, this Administration has a duty to protect the constitutional prerogatives of the Executive Branch. The committees’ 'impeachment inquiry' is entirely unprecedented and occupies a novel realm that is neither general oversight nor impeachment. As the White House Counsel explained, 'you simply cannot expect to rely on oversight authority to gather information for an unauthorized impeachment inquiry that conflicts with all historical precedent and rides roughshod over due process and the separation of powers.' Therefore, without waiving any other objections to the subpoena that OMB may have, OMB is unable to comply with your request for documents at this time," the letter says.