President Donald Trump on Friday lost his appeal to stop a House subpoena of his tax documents from his longtime accountant Mazars USA.

In a 2-1 ruling, the US Court of Appeals for the District of Columbia Circuit upheld a lower court ruling saying the firm must turn over eight years of accounting records.

It's the first major case at the appeals court level in the ongoing standoff between the House and Trump. The President has lost all of his challenges so far that have been decided at the trial court level to stop House subpoenas.

Trump may appeal to the Supreme Court to stop Mazars, but courts including the Supreme Court previously have refused to curtail Congress' subpoena power.

The appeals court broadly supported the House's power to subpoena information about Trump as it investigates him and considers laws in response, calling the subpoena "valid and enforceable."

"A congressional committee, as committees have done repeatedly over the past two centuries, issued an investigative subpoena, and the target of that subpoena, questioning the committee's legislative purpose, has asked a court to invalidate it," the majority opinion states. "The fact that the subpoena in this case seeks information that concerns the President of the United States adds a twist, but not a surprising one."

Judges David Tatel, an appointee of President Bill Clinton, wrote the majority opinion, joined by Judge Patricia Millett, an appointee of President Barack Obama. Trump appointee Judge Neomi Rao dissented.

Though the court's decision was split, the case is widely considered to be a tough one for Trump, even with support from the Justice Department.

"We detect no inherent constitutional flaw in laws requiring Presidents to publicly disclose certain financial information. And that is enough," the opinion states.

The documents the House seeks are relevant to the investigation, the majority said.

"Just as a congressional committee could not subpoena the President's high school transcripts in service of an investigation into K-12 education, nor subpoena his medical records as part of an investigation into public health, it may not subpoena his financial information except to facilitate an investigation into presidential finances" the majority opinion states.