House Democrats will send the IRS a request for at least the past 10 years of President Trump’s personal tax returns within weeks, NBC News reported Friday.

The request currently being prepared by the House Ways and Means Committee has the full support of Democratic leadership, per NBC.

“We will take all necessary steps, including litigation, if necessary, to obtain them,” Ashley Etienne, spokesperson for House Speaker Nancy Pelosi (D-CA) told NBC, citing the compelling “legitimate legislative, oversight and legal reasons” to review the documents.

Trump’s tax returns have long been a white whale for Democrats eager to determine if they can prove that the President committed tax fraud or engaged in untoward foreign dealings.

But Michael Cohen’s congressional testimony this week strengthened Democrats’ motivation for requesting them from the IRS, Democratic aides told NBC.

Cohen testified that Congress could find in Trump’s tax returns proof that the President alternately deflated the value of his assets to lower his taxes and inflated their value to insurance companies as it suited his business interests.

“Would it help for the committee to obtain federal and state tax returns from the president and his company to address that discrepancy?” Rep. Alexandria Ocasio-Cortez (D-NY) asked Cohen at one point during his testimony before the House Oversight Committee.

“I believe so,” Cohen replied.

Trump is the first president since Richard Nixon to decline to voluntarily make his tax returns public.

The decision to grant congressional Democrats’ request will rest in the hands of Treasury Secretary Steve Mnuchin.