Treasury Secretary Steve Mnuchin said Wednesday that neither Donald Trump nor “anyone in the White House” has ever asked him to withhold the president’s tax returns from Congress, which has sought up to six years of past returns in sweeping investigations into his personal finances.

“I’ve had no conversations ever with the president or anyone in the White House about delivering the president’s tax returns to Congress,” Mnuchin said during a hearing before the House Financial Services Committee and Chair Maxine Waters.

Trump has refused to turn over his tax returns, citing an ongoing audit, breaking with a practice followed by every U.S. president since Richard Nixon.

Democrats continue what Trump calls “presidential harassment” and digging into his personal, private records to smear him politically. House Democrats have demanded access to the tax returns in question by citing an obscure law from 1924 that says the Treasury secretary “shall furnish” them whenever requested by lawmakers.

Mnuchin has so far declined to hand them over, defying yet another subpoena from the House Ways and Means Committee on Friday on the basis that the requests so far lack “a legitimate legislative purpose.”

The Washington Post on Tuesday published a confidential draft of an IRS memo that is contradictory to Mnuchin’s logic.

The memo says the law “does not allow the Secretary to exercise discretion” with releasing the tax returns, and that the “only basis (for) the agency’s refusal to comply with a committee’s subpoena would be the invocation of the doctrine of executive privilege.”

Since Mnuchin testified that neither Trump nor anyone at the White House has asked him to keep the returns under lock and key, no executive privilege has been established.

Mnuchin said Wednesday the memo was “addressing a different issue,” and warned against “weaponizing” the IRS.

“I became aware of that memo when we got an inquiry from the Washington Post,” Mnuchin said. “We are trying to find out who wrote the memo, where it came from, when it was, and why it wasn’t distributed.”

A lawsuit to enforce the subpoena and get the returns could come as soon as this week, according to Richard Neal, D-Mass., the chair of the House Ways and Means Committee.