An unnamed tipster gave a House panel “credible allegations” about potential attempts to influence the Internal Revenue Service’s audit of the president’s tax returns, according to a Tuesday court filing.

The filing comes in a lawsuit filed by the House Ways and Means Committee against the Trump administration, seeking to force the government to comply with a statutory demand from committee chair Rep. Richard Neal (D-MA) for President Trump’s tax returns.

In an Aug. 8 letter to Treasury Secretary Steve Mnuchin, Neal wrote that his committee had “received an unsolicited communication from a Federal employee setting forth credible allegations of ‘evidence of possible misconduct.'”

Those allegations go to “potential ‘inappropriate efforts to influence'” the IRS’s mandatory audit of every president, Neal wrote.

The claim could be a boon for the lawsuit. Since the Democrats took the majority, Neal has predicated the much-awaited request on the need to verify whether the IRS is effectively and impartially auditing its boss, President Trump.

Neal took the same tack in the lawsuit, claiming that Trump – and Mnuchin – had prevented the committee from exercising its right to oversee the executive branch.

In the letter to Mnuchin, the Massachusetts congressman called the allegation a “grave charge” that intensified his panel’s “concerns about the absence of appropriate safeguards” in the IRS’s examination of the President’s taxes.

Neal demanded that Mnuchin provide additional information to Ways and Means in the letter, vaguely describing the records sought as “certain documents and communications of specified Treasury and IRS employees.”

Neal gave Mnuchin an Aug. 13 deadline to respond – on that day, according to another letter filed in the case, the Treasury secretary replied to say that he had referred the matter to the Treasury Secretary inspector general.

Read Neal’s letter to Mnuchin here: