An Internal Revenue Service (IRS) bureaucrat has filed a so-called “whistleblower” complaint claiming he received information that at least one Treasury Department political appointee moved to “improperly interfere” with the annual audit of President Donald Trump or Vice President Mike Pence’s tax returns, according to the Washington Post.

The Post, citing multiple anonymous sources, cannot provide key details of the complaint due to privacy laws that prohibit the disclosure of details concerning tax return filings. The complaint’s existence was revealed in court filings earlier, though it failed to garner much public attention. Two Trump administration officials downplayed the complaint due to the fact that it is based on “hearsay” and suggested it could have been prompted by political bias.

Rep. Richard E. Neal (D-MA), who chairs the House Ways and Means Committee, received the complaint in July and claims it includes evidence of “potential ‘inappropriate efforts to influence’ the audit program.”

The Washington Post reports:

The whistleblower, a career official at the IRS, confirmed in an interview with The Washington Post this week that he had filed a formal complaint and sent it to the tax committee chairs in both houses of Congress, including Sen. Charles E. Grassley (R-Iowa), and to the Treasury Department Inspector General for Tax Administration on July 29. […]

Neal has not revealed whether the whistleblower complaint is about Trump or Pence, but he said in an August court filing that the allegations “cast doubt” on the Trump administration’s contention that there is no reason for concern that IRS employees could face interference when auditing a president’s tax returns. […] The Post has been unable to verify the allegation in the whistleblower’s complaint of improper communication between Treasury and IRS on the tax audit program.

Treasury Secretary Steven Mnuchin has disclosed to Neal that his office transmitted the complaint to the inspector general.

In June, the House Ways and Means Committee filed a lawsuit against the Treasury Department and the IRS in an effort to obtain President Trump’s tax returns. At the time, Neal said his panel doesn’t need to justify why lawmakers seek the president’s tax return information. The panel stated that the administration defied a subpoena for the records “in order to shield President Trump’s tax return information from Congressional scrutiny.”

“In refusing to comply with the statute, Defendants have mounted an extraordinary attack on the authority of Congress to obtain information needed to conduct oversight of Treasury, the IRS, and the tax laws on behalf of the American people who participate in the nation’s voluntary tax system,” read the lawsuit.

“The Committee has been unable to evaluate President Trump’s claims about the audit program or investigate its other concerns because the President has declined to follow the practice of every elected President since Richard Nixon of voluntarily disclosing their tax returns,” court filings state.

“Without reviewing the requested return materials, the committee cannot ensure that the IRS’s audit process is functioning fairly and effectively, understand how provisions of the tax code are implicated by President Trump’s returns, or exercise its legislative judgment to determine whether changes to the code may be warranted,” it continues.

The Treasury Department did not issue a statement in response to the Post’s report.

The AP contributed to this report.